MySQL用户管理及SQL语句详解
<span class="log-zd"><span class="log-close"><a title="隐藏目录"><i class="be be-cross"></i><strong>目录</strong></a></span></span>
1.1 MySQL用户管理
1.1.1 用户的定义
** 用户名+**主机域
1.1.2 用户的作用
1、用户登录
2、用于管理数据库及数据
1.1.3 连接数据库
定义用户：用户名+主机域，密码
定义权限：对不同的对象进行权限(角色)定义
命令:
权限
角色
权限范围
用户
1.1.4 【练习题】按照要求创建用户
用户只能通过10.0.0.0/24网段访问，用户名为clsn 密码为123
这个用户只能对clsn数据库下的对象进行增insert create、改update 、查select；
创建命令：
查看用户权限
查看当前存在的用户:
创建用户语法
示例：
注意这个样创建的用户只有连接权限
企业里创建用户一般是授权一个内网网段登录，最常见的网段写法有两种。
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<span style="color: #ff6600;"><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">方法</span><span lang="EN-US">2</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">：</span></span><span lang="EN-US">172.16.1.0/255.255.255.0</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">，但是不能使用</span><span lang="EN-US">172.16.1.0/24</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">，是个小遗憾。</span>
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标准的建用户方法：
查看用户对应的权限
1.1.5 用户删除
删除用户语法：
【练习】用户优化：只保留
特殊的删除方法:(慎用，尽量不要直接去修改表)
1.1.6 用户授权
给用户授权
创建用户的同时授权
创建用户然后授权
授权和root一样的权限
授权给用户select,create,insert,update 权限
回收权限
可以授权的用户权限
【示例】博客授权收回示例
授权博客类的最多权限：select,insert,update,delete
1.2 MySQL 客户端工具
1.2.1 MysQL客户端命令介绍
** mysql**命令客户端
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;"> 将</span> <span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">用户</span><span lang="EN-US">SQL </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">语句发送到服务器</span>
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** mysqladmin**命令 ：命令行管理工具
** mysqldump**命令 ：备份数据库和表的内容
1.2.2 mysql命令说明
用于连接数据库
用于管理数据库通过下列方式进行管理
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<span lang="EN-US"> DDL</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">：数据定义语言</span>
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<span lang="EN-US"> DCL</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">：数据控制语言</span>
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<span lang="EN-US"> DML</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">：数据操作语言</span>
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** mysql**命令接口自带命令说明
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">命令说明</span></strong>
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<strong><span lang="EN-US">\h </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> help </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> ? </span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">获取帮助</span>
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<strong><span lang="EN-US">\G</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">格式化输出（行转列）</span>
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<strong><span lang="EN-US">\T </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> tee</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">记录操作日志</span><span lang="EN-US"> tee /tmp/mysql.log</span>
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<strong><span lang="EN-US">\c </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> CTRL+c </span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">退出</span><span lang="EN-US">mysql</span>
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<strong><span lang="EN-US">\s </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> status</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">查看数据库状态信息</span>
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<strong><span lang="EN-US">\. </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> source </span></strong>
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<span lang="EN-US">mysql> source /tmp/world.sql</span>
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<strong><span lang="EN-US">\!</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">使用</span><span lang="EN-US">shell</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">中的命令</span>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';"> <span class="cnblogs_code">mysql<span style="color: #808080;">></span> \! cat <span style="color: #808080;">/</span>etc<span style="color: #808080;">/</span>redhat<span style="color: #808080;">-</span><span style="color: #000000;">release </span></span></span>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';"><span class="cnblogs_code"><span style="color: #000000;">CentOS release </span><span style="color: #800000; font-weight: bold;">6.9</span> (Final)</span> </span>
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<strong><span lang="EN-US">\u </span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US">use </span></strong>
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<span lang="EN-US">use world </span>
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<span lang="EN-US">show databases </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">看当前所有数据库的名字</span>
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<span lang="EN-US">show tables </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">查看当前</span><span lang="EN-US">use</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">到的数据库所有的表</span>
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<span lang="EN-US">show tables from world </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">查看目标数据库下的表</span>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">快捷键</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">上下翻页、</span><span lang="EN-US">TAB</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">键、</span><span lang="EN-US">ctrl +C </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">、</span><span lang="EN-US">ctrl +L</span>
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1.2.2.1 mysql中help命令的使用
在mysql命令行中输入mysql或 ?都可以查看帮助
有关特定 SQL 类别或语句的帮助
查看 grant 的帮助
有关与状态相关的 SQL 语句的帮助
1.2.2.2 source命令的使用
在 mysql 中处理输入文件：
使用 SOURCE 命令：
或者使用非交互式：(尽量避免使用mysql 导入数据，会产生大量的无用日志)
1.2.3 mysqladmin命令说明
基本语法
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">说明</span></strong>
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<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span><span lang="EN-US"> ping</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">“强制回应</span><span lang="EN-US"> (Ping)</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">”服务器。</span>
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<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">shutdown</span></strong>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">关闭服务器。</span>
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<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">create databasename</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">创建数据库。</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span><span lang="EN-US">drop databasename</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">删除数据库</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">version</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">显示服务器和版本信息</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">status</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">显示或重置服务器状态变量</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">password</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">设置口令</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">flush-privileges</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">重新刷新授权表。</span>
</p>
</td>
</tr>
<tr>
<td style="width: 339.95pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="453">
<p class="MsoNormal">
<strong><span lang="EN-US">mysqladmin -u</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">用户</span><span lang="EN-US"> -p</span></strong><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">密码</span> <span lang="EN-US">flush-logs</span></strong>
</p>
</td>
<td style="width: 182.85pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="244">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">刷新日志文件和高速缓存。</span>
</p>
</td>
</tr>
<tr>
<td style="width: 522.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" colspan="2" valign="top" width="697">
<p class="MsoNormal">
<span style="color: #ff6600;"><strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">以上信息通过</span><span lang="EN-US">mysqladmin --help </span></strong></span><strong><span style="font-family: 微软雅黑, sans-serif; color: #ff6600;">获得</span></strong>
</p>
</td>
</tr>
</table>
1.2.4 mysqldump简单说明
mysqldump是一款数据库备份工具。
命令帮助及基本语法：
1.3 SQL语句入门
1.3.1 DDL语句(数据定义语言)
定义范围：
<p class="a">
<span lang="EN-US"> </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">表：表名字、列</span>
</p>
1.3.1.1 数据库查看
查看数据库–查看全部
查看数据库–模糊匹配
查看你相关的帮助
1.3.1.2 数据库操作
创建一个数据库
通过show 命令能够查看创建的数据库的格式
创建数据库时定义字符编码
存在的数据库修改字符编码：
修改数据库编码格式示例
mysql> show create database haha;
+–——–+————————————————————–+
| Database | Create Database |
+–——–+————————————————————–+
| haha | CREATE DATABASE haha /!40100 DEFAULT CHARACTER SET gbk / |
+–——–+————————————————————–+
1 row in set (0.00 sec)
查看支持的字符集和校对规则.
删除数据库
mysql> show databases; +–——————+ | Database |
切库
查看当前所在数据库
查看当前登陆的用户
查看库里面的表
1.3.1.3 DDL语句之管理表
表的属性：
<p class="a" style="text-indent: 21pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">默认：字符集、引擎</span>
</p>
表定义（列）：
<p class="a" style="text-indent: 21pt; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 宋体; mso-hansi-font-family: 宋体;">列属性（数据类型、列约束）</span>
</p>
创建表
创建更多的表；
查看表结构
查看建表语句
1.3.1.4 修改表的定义
修改表名字
mysql> show tables ; +–————–+ | Tables_in_clsn | +–————–+ | haha |
修改表名字，方法二。
修改表结构
指定添加年龄列到name列后面的位置，示例如下：
mysql> desc people; +–—–+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–—–+———-+——+—–+———+——-+ | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | name | int(40) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–—–+———-+——+—–+———+——-+ 4 rows in set (0.00 sec)
通过下面的命令在第一列添加qq字段。
mysql> desc people; +–——+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–——+———-+——+—–+———+——-+ | telnum | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | name | int(40) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–——+———-+——+—–+———+——-+ 5 rows in set (0.00 sec)
同时添加多个列定义：
mysql> desc people; +–——+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–——+———-+——+—–+———+——-+ | id1 | int(11) | YES | | NULL | | | telnum | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | name | int(40) | YES | | NULL | | | sex | char(4) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–——+———-+——+—–+———+——-+ 7 rows in set (0.00 sec)
mysql> desc people; +–——+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–——+———-+——+—–+———+——-+ | id1 | int(11) | YES | | NULL | | | telnum | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | name | int(40) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–——+———-+——+—–+———+——-+ 6 rows in set (0.00 sec)
修改表定义
mysql> desc people; +–——+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–——+———-+——+—–+———+——-+ | id1 | int(11) | YES | | NULL | | | telnum | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | name | char(20) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–——+———-+——+—–+———+——-+ 6 rows in set (0.00 sec)
修改列名：
mysql> desc people; +–———–+———-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–———–+———-+——+—–+———+——-+ | id1 | int(11) | YES | | NULL | | | telnum | int(11) | YES | | NULL | | | id | int(11) | YES | | NULL | | | addr | char(40) | NO | | NULL | | | people_name | char(30) | YES | | NULL | | | age | int(4) | YES | | NULL | | +–———–+———-+——+—–+———+——-+ 6 rows in set (0.00 sec)
1.3.1.5 DDL语句小结
1.3.2 DCL数据库控制语言
**grant：**用户授权
创建用户的同时进行授权
**revoke：**回收权限
收回权限示例：
1.3.3 DML数据库操作语言
DML是针对数据行的操作
1.3.3.1 insert 语句
insert 语法结构
创建表，插入数据
表的类型
在表中插入第一行数据
mysql> select * from clsn; +–—-+——+ | id | name | +–—-+——+ | 1 | clsn | +–—-+——+ 1 row in set (0.00 sec)
插入两行数据
mysql> select * from clsn; +–—-+———-+ | id | name | +–—-+———-+ | 1 | clsn | | 2 | yougboy | | 3 | youggilr | +–—-+———-+ 3 rows in set (0.00 sec)
仅在name下插入一个名字
mysql> select * from clsn; +–—-+———-+ | id | name | +–—-+———-+ | 1 | clsn | | 2 | yougboy | | 3 | youggilr | | NULL | xiaoming | +–—-+———-+ 4 rows in set (0.00 sec)
一次插入多行数据
mysql> insert into test2 select * from clsn; Query OK, 4 rows affected (0.01 sec) Records: 4 Duplicates: Warnings:
mysql> select * from test2; +–—-+———-+ | id | name | +–—-+———-+ | 1 | clsn | | 2 | yougboy | | 3 | youggilr | | NULL | xiaoming | +–—-+———-+ 4 rows in set (0.00 sec)
1.3.3.2 update更改数据库(一定要加上where条件)
更新表内容
将字段中的youggirl改为haha
更改后
1.3.3.3 delete删除表内容(一定要有where条件)
_ 删除语句_
删除xiaoming的记录
删除之后
1.3.3.4 生产中的伪删除
为表添加一个state列
_ TINYINT_ ，字段类型，如果设置为UNSIGNED类型，只能存储从0到255的整数,不能用来储存负数。
mysql> desc test2; +–—–+————-+——+—–+———+——-+ | Field | Type | Null | Key | Default | Extra | +–—–+————-+——+—–+———+——-+ | id | int(11) | YES | | NULL | | | name | varchar(20) | YES | | NULL | | | state | tinyint(2) | NO | | 1 | | +–—–+————-+——+—–+———+——-+ 3 rows in set (0.00 sec) mysql> update test set state=1;
查看当前的state状态
更新数据，将clsn记录的state改为0
mysql> select * from test2; +–—-+———+——-+ | id | name | state | +–—-+———+——-+ | 1 | clsn | | | 2 | yougboy | 1 | | 3 | haha | 1 | +–—-+———+——-+ 3 rows in set (0.00 sec)
查询的时候，使用 where 条件只显示 state=1 的记录，效果与删除类似。
1.3.3.5 防止不加条件误删【安全】
备份数据备用
mysql -U 参数实践
使用update与delete命令的时候不加where 条件不会执行。
在mysql命令加上选项-U后，当发出没有WHERE或LIMIT关键字的UPDATE或DELETE时，mysql程序拒绝执行。
1.3.4 DQL数据查询语言标准语法
1.3.4.1 语法说明
select****命令语法：
1.3.4.2 查看操作
查看用户的连接信息
查看test2表中的所有信息
查看test表中的id和name
查看id等于2 的信息
查看名字是clsn的记录
查看id大于2的记录
查看id大于2 并且 小于4的记录
查看id大于2或者 小于4的记录
提取记录排序
mysql> select id,name from test2 order by id desc; +–—-+———+ | id | name | +–—-+———+ | 3 | haha | | 2 | yougboy | | 1 | clsn | +–—-+———+ 3 rows in set (0.00 sec)
显示排错第一行后的三行(需要与排序配合使用)
1.3.5 字符集说明
1.3.5.1 常用的字符集
MySQL数据库的字符集：字符集（CHARACTER）、校对规则（COLLATION）
MySQL中常见的字符集：UTF8、LATIN1、GBK
常见校对规则：ci：大小写不敏感、cs或bin：大小写敏感
我们可以使用以下命令查看：show charset; 、 show collation；
1.3.5.2 字符集设置
系统字符集说明
客户端字符集说明
方法1：在编译安装时候就指定如下服务器端字符集。
方法2：在my.cnf文件中添加上字符参数
数据库中的库级别设置
获取帮助并查询
表级别（含字段级别）
1.3.5.3 MySQL客户端级别（连接及返回结果）
方法1：临时生效单条命令法。
方法2：通过修改my.cnf实现修改mysql客户端的字符集，配置方法如下
程序代码级别：生产环境更改数据库（含数据）字符集的方法
1.3.6 常用的查询操作
查看 当前所在的数据库
查看当前的登陆用户
1.4 数据类型说明
1.4.1 ER模型
ER模型，全称为实体联系模型、实体关系模型或实体联系模式图（ERD）（英语：Entity-relationship model）由美籍华裔计算机科学家陈品山发明，是概念数据模型的高层描述所使用的数据模型或模式图。
ER模型常用于信息系统设计中；比如它们在概念结构设计阶段用来描述信息需求和／或要存储在数据库中的信息的类型。但是数据建模技术可以用来描述特定论域（就是感兴趣的区域）的任何本体（就是对使用的术语和它们的联系的概述和分类）。在基于数据库的信息系统设计的情况下，在后面的阶段（通常叫做逻辑设计），概念模型要映射到逻辑模型如关系模型上；它依次要在物理设计期间映射到物理模型上。注意，有时这两个阶段被一起称为“物理设计”。
实体联系模式图（ERD）有一些约定。本文的余下部分描述经典概念，并且主要与概念建模有关。有一些概念更加典型的在逻辑和物理数据库设计中采用，包括信息工程、IDEF1x（ICAM DEFinition Language）和空间建模。
1.4.2 数据类型介绍
** 四种主要类别：**数值类型、字符类型、时间类型、二进制类型
1.4.3 创建带有数据类型的表
例 1：列声明
例 2：不允许负值和未知值
1.4.4 数值数据类型
使用数值数据类型时的注意事项：
- 数据类型所表示的值的范围
- 列值所需的空间量
- 列精度和范围（浮点数和定点数）
数值数据类型的类：
- 整数：整数
- 浮点数：小数
- 定点数：精确值数值
- BIT：位字段值
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">类型</span></strong>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">说明</span></strong>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
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<span lang="EN-US">TINYINT</span>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">极小整数数据类型（</span><span lang="EN-US">0-255</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">）</span>
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<tr>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
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<span lang="EN-US">SMALLINT</span>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">较小整数数据类型（</span><span lang="EN-US">-2^15 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">到</span><span lang="EN-US">2^15-1</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">）</span>
</p>
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</tr>
<tr>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
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<span lang="EN-US">MEDIUMINT</span>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">中型整数数据类型</span>
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</tr>
<tr>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
</p>
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<p class="MsoNormal" style="text-align: center;" align="center">
<span lang="EN-US">INT</span>
</p>
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<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">常规（平均）大小的整数数据类型（</span><span lang="EN-US">-2^31 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">到</span><span lang="EN-US">2^31-1</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">）</span>
</p>
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</tr>
<tr>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
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<span lang="EN-US">BIGINT</span>
</p>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">较大整数数据类型（</span><span lang="EN-US">-2^63</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">到</span><span lang="EN-US">2^63-1</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">）</span>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">浮点数</span></strong>
</p>
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<span lang="EN-US">FLOAT</span>
</p>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">小型单精度（四个字节）浮点数</span>
</p>
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</tr>
<tr>
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<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">浮点数</span></strong>
</p>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 64;" align="center">
<span lang="EN-US">DOUBLE</span>
</p>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">常规双精度（八个字节）浮点数</span>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">定点数</span></strong>
</p>
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<p class="MsoNormal" style="text-align: center;" align="center">
<span lang="EN-US">DECIMAL</span>
</p>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">包含整数部分、小数部分或同时包括二者的精确值数值</span>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">BIT</span></strong>
</p>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 64;" align="center">
<span lang="EN-US">BIT</span>
</p>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">位字段值</span>
</p>
</td>
</tr>
</table>
1.4.5 字符串数据类型
表示给定字符集中的一个字母数字字符序列，用于存储文本或二进制数据，几乎在每种编程语言中都有实现，支持字符集和整理。
属于以下其中一类
文本：真实的非结构化字符串数据类型
整数：结构化字符串类型
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">类型</span></strong>
</p>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">说明</span></strong>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">CHAR</span>
</p>
</td>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">固定长度字符串，最多为</span><span lang="EN-US">255 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">VARCHAR</span>
</p>
</td>
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<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">可变长度字符串，最多为</span><span lang="EN-US">65,535 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
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<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">TINYTEXT</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">可变长度字符串，最多为</span><span lang="EN-US">255 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
<td style="width: 77.75pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="104">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">TEXT</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">可变长度字符串，最多为</span><span lang="EN-US">65,535 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
<td style="width: 77.75pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="104">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">MEDIUMTEXT</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">可变长度字符串，最多为</span><span lang="EN-US">16,777,215 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
<td style="width: 77.75pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="104">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">文本</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">LONGTEXT</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">可变长度字符串，最多为</span><span lang="EN-US">4,294,967,295 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字符</span>
</p>
</td>
</tr>
<tr>
<td style="width: 77.75pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="104">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">ENUM</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">由一组固定的合法值组成的枚举</span>
</p>
</td>
</tr>
<tr>
<td style="width: 77.75pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="104">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">整数</span></strong>
</p>
</td>
<td style="width: 120.45pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="161">
<p class="MsoNormal">
<span lang="EN-US">SET</span>
</p>
</td>
<td style="width: 324.6pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="433">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">由一组固定的合法值组成的集</span>
</p>
</td>
</tr>
</table>
1.4.6 二进制字符串数据类型
字节序列：二进制位按八位分组
存储二进制值，例如：编译的计算机程序和应用程序、图像和声音文件
字符二进制数据类型的类：
二进制：固定长度和可变长度的二进制字符串
BLOB：二进制数据的可变长度非结构化集合
<td style="width: 106.3pt; border-top-width: 1pt; border-top-color: #4f81bd; border-left: none; border-bottom-width: 1pt; border-bottom-color: #4f81bd; border-right: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">类型</span></strong>
</p>
</td>
<td style="width: 352.95pt; border-top-width: 1pt; border-right-width: 1pt; border-bottom-width: 1pt; border-top-color: #4f81bd; border-right-color: #4f81bd; border-bottom-color: #4f81bd; border-left: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">说明</span></strong>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">二进制</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">BINARY</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">类似于</span><span lang="EN-US"> CHAR</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">（固定长度）类型，但存储的是二进制字节字符串，而不是非二进制字符串</span>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">二进制</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">VARBINARY</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">类似于</span><span lang="EN-US"> VARCHAR</span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">（可变长度）类型，但存储的是二进制字节字符串，而不是非二进制字符串</span>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">BLOB</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">TINYBLOB</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">最大长度为</span><span lang="EN-US">255 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字节的</span><span lang="EN-US"> BLOB </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">列</span>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span lang="EN-US">BLOB</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">BLOB</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">最大长度为</span><span lang="EN-US">65,535 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字节的</span><span lang="EN-US"> BLOB </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">列</span>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">BLOB</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">MEDIUDMBLOB</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">最大长度为</span><span lang="EN-US">16,777,215 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字节的</span><span lang="EN-US"> BLOB </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">列</span>
</p>
</td>
</tr>
<tr>
<td style="width: 63.55pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="85">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span lang="EN-US">BLOB</span></strong>
</p>
</td>
<td style="width: 106.3pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="142">
<p class="MsoNormal">
<span lang="EN-US">LONGBLOB</span>
</p>
</td>
<td style="width: 352.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="471">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">最大长度为</span><span lang="EN-US">4,294,967,295 </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">个字节的</span><span lang="EN-US"> BLOB </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">列</span>
</p>
</td>
</tr>
</table>
1.4.7 时间数据类型
<td style="width: 219.75pt; border-top-width: 1pt; border-top-color: #4f81bd; border-left: none; border-bottom-width: 1pt; border-bottom-color: #4f81bd; border-right: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">格式</span></strong>
</p>
</td>
<td style="width: 218.25pt; border-top-width: 1pt; border-right-width: 1pt; border-bottom-width: 1pt; border-top-color: #4f81bd; border-right-color: #4f81bd; border-bottom-color: #4f81bd; border-left: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">示例</span></strong>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">DATE</span></strong>
</p>
</td>
<td style="width: 219.75pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal">
<span lang="EN-US">YYYY-MM-DD</span>
</p>
</td>
<td style="width: 218.25pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal">
<span lang="EN-US">2017-12-16</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span lang="EN-US">TIME</span></strong>
</p>
</td>
<td style="width: 219.75pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal">
<span lang="EN-US">hh:mm:ss[.uuuuuu]</span>
</p>
</td>
<td style="width: 218.25pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal">
<span lang="EN-US">12:59:02.123456</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">DATETIME</span></strong>
</p>
</td>
<td style="width: 219.75pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal">
<span lang="EN-US">YYYY-MM-DD hh:mm:ss[.uuuuuu]</span>
</p>
</td>
<td style="width: 218.25pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal">
<span lang="EN-US">2017-12-16 12:59:02.123</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span lang="EN-US">TIMESTAMP</span></strong>
</p>
</td>
<td style="width: 219.75pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal">
<span lang="EN-US">YYYY-MM-DD hh:mm:ss[.uuuuuu]</span>
</p>
</td>
<td style="width: 218.25pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal">
<span lang="EN-US">2017-12-16 12:59:02.12</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span lang="EN-US">YEAR</span></strong>
</p>
</td>
<td style="width: 219.75pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="293">
<p class="MsoNormal">
<span lang="EN-US">YYYY</span>
</p>
</td>
<td style="width: 218.25pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="291">
<p class="MsoNormal">
<span lang="EN-US">2017</span>
</p>
</td>
</tr>
</table>
1.4.8 列属性
列属性的类别：
数值：适用于数值数据类型（BIT 除外）
字符串：适用于非二进制字符串数据类型
常规：适用于所有数据类型
<td style="width: 155.95pt; border-top-width: 1pt; border-top-color: #4f81bd; border-left: none; border-bottom-width: 1pt; border-bottom-color: #4f81bd; border-right: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">属性</span></strong>
</p>
</td>
<td style="width: 282.05pt; border-top-width: 1pt; border-right-width: 1pt; border-bottom-width: 1pt; border-top-color: #4f81bd; border-right-color: #4f81bd; border-bottom-color: #4f81bd; border-left: none; background: #4f81bd; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 1;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New'; color: white; mso-themecolor: background1;">说明</span></strong>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">数值</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">UNSIGNED</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">禁止使用负值</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">仅整数</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">AUTO_INCREMENT</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">生成包含连续唯一整数值的序列</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">字符串</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">CHARACTER SET</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">指定要使用的字符集</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">字符串</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">COLLATE</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">指定字符集整理</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">字符串</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">BINARY</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">指定二进制整理</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 4;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">全部</span><span lang="EN-US">*</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">NULL </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">或</span><span lang="EN-US"> NOT NULL</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">指示列是否可以包含</span><span lang="EN-US"> NULL </span><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">值</span>
</p>
</td>
</tr>
<tr>
<td style="width: 84.8pt; border-right-width: 1pt; border-bottom-width: 1pt; border-left-width: 1pt; border-right-color: #95b3d7; border-bottom-color: #95b3d7; border-left-color: #95b3d7; border-top: none; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="113">
<p class="MsoNormal" style="text-align: center; mso-yfti-cnfc: 68;" align="center">
<strong><span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">全部</span></strong>
</p>
</td>
<td style="width: 155.95pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="208">
<p class="MsoNormal">
<span lang="EN-US">DEFAULT</span>
</p>
</td>
<td style="width: 282.05pt; border-top: none; border-left: none; border-bottom-width: 1pt; border-bottom-color: #95b3d7; border-right-width: 1pt; border-right-color: #95b3d7; background: #dbe5f1; padding: 0cm 5.4pt;" valign="top" width="376">
<p class="MsoNormal">
<span style="font-family: '微软雅黑',sans-serif; mso-ascii-font-family: 'Courier New'; mso-hansi-font-family: 'Courier New';">如果未为新记录指定值，则为其提供默认值</span>
</p>
</td>
</tr>
</table>
1.4.9 数据类型小结
使用固定长度数据类型：
如果存储的所有字符串值的长度相同
使用可变长度数据类型：
如果存储的字符串值不同、对于多字节字符集
对于频繁使用的字符，使用占用空间较少的多字节字符集。
使用基本多文种平面 (Basic Multilingual Plane, BMP) 之外的其他、Unicode 字符集。
1.5开发人员SQL规范:
1、合适的数据类型 2、定义合理的数据长度 3、建表时，同时设置字符集、校对规则、存储引擎类型 4、表名、列名必须有意义，每个列要有描述字段（注释字段 COMMENT ‘素材类型’） 5、每个表都，定义无关列，设置为自增长（AUTO_INCREMENT） 6、每个表都有主键列，一般是设置在无关列上 PRIMARY KEY (ID) 7、每个列都是not null ，default。 8、列要加合适的约束条件。 9、插入数据的时候不要有空值
1.6 参考文献
<li>
<a href="#12_MySQL">1.2 MySQL 客户端工具</a><ul>
<li>
<a href="#121_MysQL">1.2.1 MysQL客户端命令介绍</a>
</li>
<li>
<a href="#122_mysql">1.2.2 mysql命令说明</a><ul>
<li>
<a href="#1221nbsp_mysqlhelp">1.2.2.1 mysql中help命令的使用</a>
</li>
<li>
<a href="#1222nbsp_source">1.2.2.2 source命令的使用</a>
</li>
</ul>
</li>
<li>
<a href="#123_mysqladmin">1.2.3 mysqladmin命令说明</a>
</li>
<li>
<a href="#124_mysqldump">1.2.4 mysqldump简单说明</a>
</li>
</ul>
</li>
<li>
<a href="#13_SQL">1.3 SQL语句入门</a>
</li>
<li>
<a href="#131_DDL">1.3.1 DDL语句(数据定义语言)</a><ul>
<li>
<ul>
<li>
<a href="#1311nbsp">1.3.1.1 数据库查看</a>
</li>
<li>
<a href="#1312nbsp">1.3.1.2 数据库操作</a>
</li>
<li>
<a href="#1313nbsp_DDL">1.3.1.3 DDL语句之管理表</a>
</li>
<li>
<a href="#1314nbsp">1.3.1.4 修改表的定义</a>
</li>
<li>
<a href="#1315nbsp_DDL">1.3.1.5 DDL语句小结</a>
</li>
</ul>
</li>
</ul>
</li>
<li>
<a href="#132_DCL">1.3.2 DCL数据库控制语言</a>
</li>
<li>
<a href="#133_DML">1.3.3 DML数据库操作语言</a><ul>
<li>
<ul>
<li>
<a href="#1331nbsp_insert">1.3.3.1 insert 语句</a>
</li>
<li>
<a href="#1332nbsp_updatewhere">1.3.3.2 update更改数据库(一定要加上where条件)</a>
</li>
<li>
<a href="#1333nbsp_deletewhere">1.3.3.3 delete删除表内容(一定要有where条件)</a>
</li>
<li>
<a href="#1334nbsp">1.3.3.4 生产中的伪删除</a>
</li>
<li>
<a href="#1335nbsp">1.3.3.5 防止不加条件误删【安全】</a>
</li>
</ul>
</li>
</ul>
</li>
<li>
<a href="#134_DQL">1.3.4 DQL数据查询语言标准语法</a><ul>
<li>
<ul>
<li>
<a href="#1341nbsp">1.3.4.1 语法说明</a>
</li>
<li>
<a href="#1342nbsp">1.3.4.2 查看操作</a>
</li>
</ul>
</li>
<li>
<a href="#135">1.3.5 字符集说明</a><ul>
<li>
<a href="#1351nbsp">1.3.5.1 常用的字符集</a>
</li>
<li>
<a href="#1352nbsp">1.3.5.2 字符集设置</a>
</li>
<li>
<a href="#1353nbsp_MySQL">1.3.5.3 MySQL客户端级别（连接及返回结果）</a>
</li>
</ul>
</li>
<li>
<a href="#136">1.3.6 常用的查询操作</a>
</li>
</ul>
</li>
<li>
<a href="#14">1.4 数据类型说明</a><ul>
<li>
<a href="#141_ER">1.4.1 ER模型</a>
</li>
<li>
<a href="#142">1.4.2 数据类型介绍</a>
</li>
<li>
<a href="#143">1.4.3 创建带有数据类型的表</a>
</li>
<li>
<a href="#144">1.4.4 数值数据类型</a>
</li>
<li>
<a href="#145">1.4.5 字符串数据类型</a>
</li>
<li>
<a href="#146">1.4.6 二进制字符串数据类型</a>
</li>
<li>
<a href="#147">1.4.7 时间数据类型</a>
</li>
<li>
<a href="#148">1.4.8 列属性</a>
</li>
<li>
<a href="#149">1.4.9 数据类型小结</a>
</li>
</ul>
</li>
<li>
<a href="#15SQL">1.5开发人员SQL规范:</a>
</li>
<li>
<a href="#16">1.6 参考文献</a>
</li>
- 原文作者：惨绿少年
- 原文链接：https://clsn.io/clsn/lx442.html
- 版权声明：本作品采用知识共享署名-非商业性使用-禁止演绎 4.0 国际许可协议进行许可，非商业转载请注明出处（作者，原文链接），商业转载请联系作者获得授权。