@shixinde/vuepress-theme-init
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import{_ as s,c as n,o as a,a as e}from"./app-Dx9bNbfq.js";const l={},t=e(`<h1 id="mysql" tabindex="-1"><a class="header-anchor" href="#mysql"><span>mySql</span></a></h1><h2 id="创建表" tabindex="-1"><a class="header-anchor" href="#创建表"><span>创建表</span></a></h2><div class="language-mysql line-numbers-mode" data-highlighter="prismjs" data-ext="mysql" data-title="mysql"><pre class="language-mysql"><code><span class="line">CREATE TABLE student(</span>
<span class="line">id int comment "编号",</span>
<span class="line">name VARCHAR(50) COMMENT "姓名",</span>
<span class="line">age int COMMENT '年龄',</span>
<span class="line">gender VARCHAR(1) comment '性别')</span>
<span class="line">comment '用户表'</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="显示当前数据库中的表" tabindex="-1"><a class="header-anchor" href="#显示当前数据库中的表"><span>显示当前数据库中的表</span></a></h2><div class="language-mysql line-numbers-mode" data-highlighter="prismjs" data-ext="mysql" data-title="mysql"><pre class="language-mysql"><code><span class="line">show tables</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h2 id="显示表结构" tabindex="-1"><a class="header-anchor" href="#显示表结构"><span>显示表结构</span></a></h2><div class="language-mySql line-numbers-mode" data-highlighter="prismjs" data-ext="mySql" data-title="mySql"><pre class="language-mySql"><code><span class="line">desc student</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><h2 id="代码片段" tabindex="-1"><a class="header-anchor" href="#代码片段"><span>代码片段</span></a></h2><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">select</span> <span class="token operator">*</span> <span class="token keyword">from</span> person <span class="token keyword">WHERE</span> id <span class="token operator">BETWEEN</span> <span class="token number">0</span> <span class="token operator">AND</span> <span class="token number">122</span> <span class="token operator">and</span> name <span class="token operator">like</span> <span class="token string">'%23'</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">select</span> <span class="token operator">*</span> <span class="token keyword">from</span> person <span class="token keyword">WHERE</span> id <span class="token operator">in</span> <span class="token punctuation">(</span><span class="token number">112</span><span class="token punctuation">,</span><span class="token number">113</span><span class="token punctuation">)</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">select</span> gender<span class="token punctuation">,</span><span class="token function">count</span><span class="token punctuation">(</span><span class="token operator">*</span><span class="token punctuation">)</span> <span class="token keyword">from</span> person <span class="token keyword">WHERE</span> id<span class="token operator"><</span><span class="token number">200</span> <span class="token keyword">GROUP</span> <span class="token keyword">BY</span> gender</span>
<span class="line"></span>
<span class="line"><span class="token keyword">SELECT</span> name<span class="token punctuation">,</span>id<span class="token punctuation">,</span>gender <span class="token keyword">from</span> person <span class="token keyword">LIMIT</span> <span class="token number">1</span><span class="token punctuation">,</span><span class="token number">1</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="管理用户" tabindex="-1"><a class="header-anchor" href="#管理用户"><span>管理用户</span></a></h2><h3 id="查询用户" tabindex="-1"><a class="header-anchor" href="#查询用户"><span>查询用户</span></a></h3><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">use</span> mysql</span>
<span class="line"><span class="token keyword">select</span> <span class="token operator">*</span> <span class="token keyword">from</span> <span class="token keyword">user</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div></div></div><h3 id="创建用户" tabindex="-1"><a class="header-anchor" href="#创建用户"><span>创建用户</span></a></h3><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">create</span> <span class="token keyword">user</span> <span class="token string">'yxd'</span><span class="token variable">@'localhost'</span> IDENTIFIED <span class="token keyword">by</span> <span class="token string">'123321'</span></span>
<span class="line"><span class="token keyword">create</span> <span class="token keyword">user</span> <span class="token string">'用户名'</span><span class="token variable">@'主机地址'</span> IDENTIFIED <span class="token keyword">by</span> <span class="token string">'密码'</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div></div></div><blockquote><p><code>localhost</code>表示本机可用</p><p>如果任意主机都需要连接的话 使用<code>'%'</code> 即可</p></blockquote><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">create</span> <span class="token keyword">user</span> <span class="token string">'用户名'</span><span class="token variable">@'%'</span> IDENTIFIED <span class="token keyword">by</span> <span class="token string">'密码'</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div></div></div><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"> <span class="token keyword">SELECT</span> NAME<span class="token punctuation">,</span></span>
<span class="line"><span class="token punctuation">(</span><span class="token keyword">CASE</span> gender <span class="token keyword">WHEN</span> <span class="token string">'男'</span> <span class="token keyword">THEN</span> <span class="token string">'小伙子'</span> <span class="token keyword">WHEN</span> <span class="token string">'女'</span> <span class="token keyword">THEN</span> <span class="token string">'女朋友'</span> <span class="token keyword">ELSE</span> <span class="token string">'狗'</span> <span class="token keyword">END</span> <span class="token punctuation">)</span><span class="token keyword">AS</span> <span class="token string">'别称'</span> </span>
<span class="line"><span class="token keyword">FROM</span> person</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">create</span> <span class="token keyword">TABLE</span> <span class="token keyword">user</span><span class="token punctuation">(</span></span>
<span class="line"> id <span class="token keyword">int</span> <span class="token keyword">PRIMARY</span> <span class="token keyword">KEY</span> <span class="token keyword">auto_increment</span> <span class="token keyword">comment</span> <span class="token string">'主键'</span><span class="token punctuation">,</span></span>
<span class="line"> name <span class="token keyword">VARCHAR</span><span class="token punctuation">(</span><span class="token number">10</span><span class="token punctuation">)</span> <span class="token operator">not</span> <span class="token boolean">NULL</span> <span class="token keyword">UNIQUE</span> <span class="token keyword">COMMENT</span> <span class="token string">'姓名'</span><span class="token punctuation">,</span></span>
<span class="line"> age <span class="token keyword">int</span> <span class="token keyword">check</span><span class="token punctuation">(</span>age<span class="token operator">></span><span class="token number">18</span> <span class="token operator">&&</span> age<span class="token operator"><</span><span class="token number">120</span><span class="token punctuation">)</span> <span class="token keyword">COMMENT</span> <span class="token string">'年龄'</span><span class="token punctuation">,</span></span>
<span class="line"> <span class="token keyword">STATUS</span> <span class="token keyword">char</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">DEFAULT</span> <span class="token string">'1'</span> <span class="token keyword">COMMENT</span> <span class="token string">'状态'</span><span class="token punctuation">,</span></span>
<span class="line"> gender <span class="token keyword">char</span><span class="token punctuation">(</span><span class="token number">1</span><span class="token punctuation">)</span> <span class="token keyword">comment</span> <span class="token string">'性别'</span></span>
<span class="line"></span>
<span class="line"><span class="token punctuation">)</span><span class="token keyword">comment</span> <span class="token string">'用户表'</span></span>
<span class="line"></span>
<span class="line"><span class="token keyword">use</span> test</span>
<span class="line"></span>
<span class="line"><span class="token keyword">INSERT</span> <span class="token keyword">into</span> <span class="token keyword">user</span><span class="token punctuation">(</span>name<span class="token punctuation">,</span>age<span class="token punctuation">,</span><span class="token keyword">status</span><span class="token punctuation">,</span>gender<span class="token punctuation">)</span> <span class="token keyword">values</span> <span class="token punctuation">(</span><span class="token string">'tom'</span><span class="token punctuation">,</span><span class="token number">19</span><span class="token punctuation">,</span><span class="token string">'1'</span><span class="token punctuation">,</span><span class="token string">'女'</span><span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token punctuation">(</span><span class="token string">'tom2'</span><span class="token punctuation">,</span><span class="token number">19</span><span class="token punctuation">,</span><span class="token string">'2'</span><span class="token punctuation">,</span><span class="token string">'男'</span><span class="token punctuation">)</span></span>
<span class="line"></span>
<span class="line"></span>
<span class="line"><span class="token keyword">select</span> <span class="token operator">*</span> <span class="token keyword">from</span> <span class="token keyword">user</span></span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="自查询" tabindex="-1"><a class="header-anchor" href="#自查询"><span>自查询</span></a></h2><blockquote><p>需要注意 子查询 必须起别名</p></blockquote><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person <span class="token keyword">JOIN</span> person <span class="token keyword">as</span> b <span class="token keyword">ON</span> person<span class="token punctuation">.</span>id <span class="token operator">=</span> b<span class="token punctuation">.</span>idCard</span>
<span class="line"></span>
<span class="line"><span class="token keyword">SELECT</span> <span class="token operator">*</span> <span class="token keyword">FROM</span> person p<span class="token punctuation">,</span>person b <span class="token keyword">WHERE</span> p<span class="token punctuation">.</span>id <span class="token operator">=</span> b<span class="token punctuation">.</span>idCard</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="合并-两个表查询后合并为新表" tabindex="-1"><a class="header-anchor" href="#合并-两个表查询后合并为新表"><span>合并 两个表查询后合并为新表</span></a></h2><blockquote><p>UNION all 合并查询 UNION 合并查询后去重</p><p>注意两个表的列数需要相同 字段类型也需要一致</p></blockquote><div class="language-text line-numbers-mode" data-highlighter="prismjs" data-ext="text" data-title="text"><pre class="language-text"><code><span class="line">select * FROM person WHERE gender= '男' </span>
<span class="line">UNION all</span>
<span class="line">SELECT * FROM person WHERE name like '张三</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h2 id="distinct-去除重复项-去重" tabindex="-1"><a class="header-anchor" href="#distinct-去除重复项-去重"><span>DISTINCT 去除重复项 去重</span></a></h2><h2 id="事务-四大特性-基本操作-隔离级别" tabindex="-1"><a class="header-anchor" href="#事务-四大特性-基本操作-隔离级别"><span>事务 四大特性 基本操作 隔离级别</span></a></h2><h3 id="四大特性acid" tabindex="-1"><a class="header-anchor" href="#四大特性acid"><span>四大特性ACID</span></a></h3><blockquote><ul><li>原子性(Atomicity)：事务是不可分割的最小操作但愿，要么全部成功，要么全部失败</li><li>一致性(Consistency)：事务完成时，必须使所有数据都保持一致状态</li><li>隔离性(Isolation)：数据库系统提供的隔离机制，保证事务在不受外部并发操作影响的独立环境下运行</li><li>持久性(Durability)：事务一旦提交或回滚，它对数据库中的数据的改变就是永久的</li></ul></blockquote><h3 id="事务的基本操作" tabindex="-1"><a class="header-anchor" href="#事务的基本操作"><span>事务的基本操作</span></a></h3><p>事务是一组操作的集合，事务会把所有操作作为一个整体一起向系统提交或撤销操作请求，即这些操作要么同时成功，要么同时失败。</p><p>基本操作：</p><div class="language-mysql line-numbers-mode" data-highlighter="prismjs" data-ext="mysql" data-title="mysql"><pre class="language-mysql"><code><span class="line">-- 1. 查询张三账户余额</span>
<span class="line">select * from account where name = '张三';</span>
<span class="line">-- 2. 将张三账户余额-1000</span>
<span class="line">update account set money = money - 1000 where name = '张三';</span>
<span class="line">-- 此语句出错后张三钱减少但是李四钱没有增加</span>
<span class="line">模拟sql语句错误</span>
<span class="line">-- 3. 将李四账户余额+1000</span>
<span class="line">update account set money = money + 1000 where name = '李四';</span>
<span class="line"></span>
<span class="line">-- 查看事务提交方式</span>
<span class="line">SELECT @@AUTOCOMMIT;</span>
<span class="line">-- 设置事务提交方式，1为自动提交，0为手动提交，该设置只对当前会话有效</span>
<span class="line">SET @@AUTOCOMMIT = 0;</span>
<span class="line">-- 提交事务</span>
<span class="line">COMMIT;</span>
<span class="line">-- 回滚事务</span>
<span class="line">ROLLBACK;</span>
<span class="line"></span>
<span class="line">-- 设置手动提交后上面代码改为：</span>
<span class="line">select * from account where name = '张三';</span>
<span class="line">update account set money = money - 1000 where name = '张三';</span>
<span class="line">update account set money = money + 1000 where name = '李四';</span>
<span class="line">commit;</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>操作方式二：</p><p>开启事务： <code>START TRANSACTION 或 BEGIN TRANSACTION;</code> 提交事务： <code>COMMIT;</code> 回滚事务： <code>ROLLBACK;</code></p><p>操作实例：</p><div class="language-mysql line-numbers-mode" data-highlighter="prismjs" data-ext="mysql" data-title="mysql"><pre class="language-mysql"><code><span class="line">start transaction;</span>
<span class="line">select * from account where name = '张三';</span>
<span class="line">update account set money = money - 1000 where name = '张三';</span>
<span class="line">update account set money = money + 1000 where name = '李四';</span>
<span class="line">commit;</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><p>并发事务</p><table><thead><tr><th>问题</th><th>描述</th></tr></thead><tbody><tr><td>脏读</td><td>一个事务读到另一个事务还没提交的数据</td></tr><tr><td>不可重复读</td><td>一个事务先后读取同一条记录，但两次读取的数据不同</td></tr><tr><td>幻读</td><td>一个事务按照条件查询数据时，没有对应的数据行，但是再插入数据时，又发现这行数据已经存在</td></tr></tbody></table><blockquote><p>这三个问题的详细演示：https://www.bilibili.com/video/BV1Kr4y1i7ru?p=55cd</p></blockquote><p>并发事务隔离级别：</p><table><thead><tr><th>隔离级别</th><th>脏读</th><th>不可重复读</th><th>幻读</th></tr></thead><tbody><tr><td>Read uncommitted</td><td>√</td><td>√</td><td>√</td></tr><tr><td>Read committed</td><td>×</td><td>√</td><td>√</td></tr><tr><td>Repeatable Read(默认)</td><td>×</td><td>×</td><td>√</td></tr><tr><td>Serializable</td><td>×</td><td>×</td><td>×</td></tr></tbody></table><ul><li>√表示在当前隔离级别下该问题会出现</li><li>Serializable 性能最低；Read uncommitted 性能最高，数据安全性最差</li></ul><p>查看事务隔离级别： <code>SELECT @@TRANSACTION_ISOLATION;</code> 设置事务隔离级别： <code>SET [ SESSION | GLOBAL ] TRANSACTION ISOLATION LEVEL {READ UNCOMMITTED | READ COMMITTED | REPEATABLE READ | SERIALIZABLE };</code> SESSION 是会话级别，表示只针对当前会话有效，GLOBAL 表示对所有会话有效</p><p>‘</p><h2 id="索引" tabindex="-1"><a class="header-anchor" href="#索引"><span>索引</span></a></h2><div class="language-sql line-numbers-mode" data-highlighter="prismjs" data-ext="sql" data-title="sql"><pre class="language-sql"><code><span class="line"><span class="token comment">-- 创建索引</span></span>
<span class="line"><span class="token keyword">create</span> <span class="token keyword">index</span> idx_student_age <span class="token keyword">on</span> student<span class="token punctuation">(</span>age<span class="token punctuation">)</span></span>
<span class="line"><span class="token comment">-- 展示表名中的所有的索引</span></span>
<span class="line"><span class="token keyword">show</span> <span class="token keyword">index</span> <span class="token keyword">from</span> student</span>
<span class="line"><span class="token comment">-- 删除索引</span></span>
<span class="line"><span class="token keyword">DROP</span> <span class="token keyword">index</span> idx_student_age <span class="token keyword">on</span> student</span>
<span class="line"></span></code></pre><div class="line-numbers" aria-hidden="true" style="counter-reset:line-number 0;"><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div><div class="line-number"></div></div></div><h1 id="学到了-65集" tabindex="-1"><a class="header-anchor" href="#学到了-65集"><span>学到了 65集</span></a></h1><p><a href="https://www.bilibili.com/video/BV1Kr4y1i7ru?p=65&vd_source=cb80c53a34a612fea928a61d4319bb8d" target="_blank" rel="noopener noreferrer">08. 进阶-MySQL安装(linux版本)_哔哩哔哩_bilibili</a></p>`,48),p=[t];function i(c,d){return a(),n("div",null,p)}const r=s(l,[["render",i],["__file","mySql.html.vue"]]),u=JSON.parse(`{"path":"/Java/mySql.html","title":"Mysql","lang":"zh-CN","frontmatter":{"title":"Mysql","date":"2023-5-21","tags":["Mysql"],"categories":["自学篇"]},"headers":[{"level":2,"title":"创建表","slug":"创建表","link":"#创建表","children":[]},{"level":2,"title":"显示当前数据库中的表","slug":"显示当前数据库中的表","link":"#显示当前数据库中的表","children":[]},{"level":2,"title":"显示表结构","slug":"显示表结构","link":"#显示表结构","children":[]},{"level":2,"title":"代码片段","slug":"代码片段","link":"#代码片段","children":[]},{"level":2,"title":"管理用户","slug":"管理用户","link":"#管理用户","children":[{"level":3,"title":"查询用户","slug":"查询用户","link":"#查询用户","children":[]},{"level":3,"title":"创建用户","slug":"创建用户","link":"#创建用户","children":[]}]},{"level":2,"title":"自查询","slug":"自查询","link":"#自查询","children":[]},{"level":2,"title":"合并 两个表查询后合并为新表","slug":"合并-两个表查询后合并为新表","link":"#合并-两个表查询后合并为新表","children":[]},{"level":2,"title":"DISTINCT 去除重复项 去重","slug":"distinct-去除重复项-去重","link":"#distinct-去除重复项-去重","children":[]},{"level":2,"title":"事务 四大特性 基本操作 隔离级别","slug":"事务-四大特性-基本操作-隔离级别","link":"#事务-四大特性-基本操作-隔离级别","children":[{"level":3,"title":"四大特性ACID","slug":"四大特性acid","link":"#四大特性acid","children":[]},{"level":3,"title":"事务的基本操作","slug":"事务的基本操作","link":"#事务的基本操作","children":[]}]},{"level":2,"title":"索引","slug":"索引","link":"#索引","children":[]}],"git":{"updatedTime":1727229103000,"contributors":[{"name":"袁果锅","email":"2914310412@qq.com","commits":1}]},"filePathRelative":"Java/mySql.md","excerpt":"\\n<h2>创建表</h2>\\n<div class=\\"language-mysql\\" data-highlighter=\\"prismjs\\" data-ext=\\"mysql\\" data-title=\\"mysql\\"><pre class=\\"language-mysql\\"><code><span class=\\"line\\">CREATE TABLE student(</span>\\n<span class=\\"line\\">id int comment \\"编号\\",</span>\\n<span class=\\"line\\">name VARCHAR(50) COMMENT \\"姓名\\",</span>\\n<span class=\\"line\\">age int COMMENT '年龄',</span>\\n<span class=\\"line\\">gender VARCHAR(1) comment '性别')</span>\\n<span class=\\"line\\">comment '用户表'</span>\\n<span class=\\"line\\"></span></code></pre></div>"}`);export{r as comp,u as data};