删除
This commit is contained in:
@@ -3,6 +3,7 @@ module.exports = {
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description: '测试',
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themeConfig: {
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search:false,
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sidebarDepth:2,
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sidebar: 'auto',
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nav: [
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@@ -14,7 +15,8 @@ module.exports = {
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'install', /* /foo/one.html */
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'create', /* /foo/two.html */
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'insert',
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'update'
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'update',
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'delete'
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] ,
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'/': [
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'', /* / */
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@@ -1,16 +1 @@
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---
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home: true
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heroImage: /hero.png
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heroText: Hero 标题
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tagline: Hero 副标题
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actionText: 快速上手 →
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actionLink: /zh/guide/
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features:
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- title: 简洁至上
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details: 以 Markdown 为中心的项目结构,以最少的配置帮助你专注于写作。
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- title: Vue驱动
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details: 享受 Vue + webpack 的开发体验,在 Markdown 中使用 Vue 组件,同时可以使用 Vue 来开发自定义主题。
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- title: 高性能
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details: VuePress 为每个页面预渲染生成静态的 HTML,同时在页面被加载的时候,将作为 SPA 运行。
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footer: MIT Licensed | Copyright © 2018-present Evan You
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---
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# 测试课程教案
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49
docs/mysql/delete.md
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49
docs/mysql/delete.md
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@@ -0,0 +1,49 @@
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# 删除数据
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> mysql删除是使用delete语句
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## delete
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删除语法其实是非常简单的,但是也是比较危险的,需要慎重操作。
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```sql
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delete from table [where ];
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```
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最简单的删除语句是
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```sql
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delete from tablename;
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```
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但是不要这么操作,他会像修改时候一样,全部删除掉,所以操作删除的时候一定要添加条件
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```sql
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delete from tablename where 条件;
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```
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还是之前的class表。
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比如我要删除姓名为张三的人,应该怎么删除呢?
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```sql
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delete from class where name = "张三";
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```
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删除成功了,然后查询之后张三就没有了。
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比如要删除年龄是18的人,那么应该就是 `where age = 18`
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```sql
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delete from class where age = 18;
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```
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成功删除了,删除了所有年龄是18的人。
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删除是比较简单的操作,接下来就要来看一下主键。
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17
docs/mysql/primaryKey.md
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17
docs/mysql/primaryKey.md
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# 主键
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> 在之前的操作中我们进行了增删改查,并没有出现什么问题,但是有一个很大的问题,前面的姓名。年龄,性别都是有可能重复的,我们没有办法准确的确定到一个人,比如下面这种情况。
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## primary key
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先看一下现在表中的数据。
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现在表中还有李四和小名这两个人,但是这个班级中又来了一个转校生,名字也叫李四,性别也是男,但是年龄是21。
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先添加这么一个人
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```sql
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insert into class(name,sex,age) value("李四","男",21);
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```
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@@ -1,8 +1,8 @@
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# 数据操作
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# 修改数据
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> 之前已经看到了查询数据与添加数据,下面来看一下修改数据
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## 修改数据
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## update
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修改数据也有自己的另一个语法。
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@@ -80,7 +80,7 @@ set 后面跟上修改的字段名=值,然后用逗号隔开 `,`
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update class set sex="男",age=10 where name="李四";
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```
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执行一下
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执行一下
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@@ -10,4 +10,4 @@
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"dev": "vuepress dev docs",
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"build": "vuepress build docs"
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}
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}
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}
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13
yarn.lock
13
yarn.lock
@@ -3631,6 +3631,11 @@ glob-to-regexp@^0.3.0:
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resolved "https://registry.yarnpkg.com/glob-to-regexp/-/glob-to-regexp-0.3.0.tgz#8c5a1494d2066c570cc3bfe4496175acc4d502ab"
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integrity sha1-jFoUlNIGbFcMw7/kSWF1rMTVAqs=
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glob-to-regexp@^0.4.1:
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version "0.4.1"
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resolved "https://registry.npm.taobao.org/glob-to-regexp/download/glob-to-regexp-0.4.1.tgz#c75297087c851b9a578bd217dd59a92f59fe546e"
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integrity sha1-x1KXCHyFG5pXi9IX3VmpL1n+VG4=
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glob@^7.0.3, glob@^7.1.2, glob@^7.1.3, glob@^7.1.4, glob@^7.1.6:
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version "7.1.6"
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resolved "https://registry.yarnpkg.com/glob/-/glob-7.1.6.tgz#141f33b81a7c2492e125594307480c46679278a6"
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@@ -7651,6 +7656,14 @@ watchpack@^1.7.4:
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chokidar "^3.4.1"
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watchpack-chokidar2 "^2.0.1"
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watchpack@^2.1.1:
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version "2.1.1"
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resolved "https://registry.nlark.com/watchpack/download/watchpack-2.1.1.tgz#e99630550fca07df9f90a06056987baa40a689c7"
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integrity sha1-6ZYwVQ/KB9+fkKBgVph7qkCmicc=
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dependencies:
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glob-to-regexp "^0.4.1"
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graceful-fs "^4.1.2"
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wbuf@^1.1.0, wbuf@^1.7.3:
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version "1.7.3"
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resolved "https://registry.yarnpkg.com/wbuf/-/wbuf-1.7.3.tgz#c1d8d149316d3ea852848895cb6a0bfe887b87df"
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