面试之SQL(2)--left join, inner join 和 right join的区别
来源:互联网 发布:数据库更新语句 编辑:程序博客网 时间:2024/06/10 05:56
表A记录如下:
aID aName
1 a1
2 a2
3 a3
4 a4
5 a5
表B记录如下:
bID bXuehao
1 2006102401
2 2006102402
3 2006102403
4 2006102404
6 2006102406
SELECT * FROM A LEFT JOIN B ON A.aID =B.bID
结果如下:
aID aName bID bXuehao
1 a1 1 2006102401
2 a2 2 2006102402
3 a3 3 2006102403
4 a4 4 2006102404
5 a5 NULL NULL
(所影响的行数为 5 行)
结果是基于A表的
SELECT * FROM A RIGHT JOING B ON A.aID = B.bID
结果如下:
aID aName bID bXuehao
1 a1 1 2006102401
2 a2 2 2006102402
3 a3 3 2006102403
4 a4 4 2006102404
NULL NULL 6 2006102406
(所影响的行数为 5 行)
结果是基于B表的
SELECT * FROM a
INNER JOIN b
ON a.aID =b.bID
等同于以下SQL句:
SELECT * FROM A,B WHERE A.aID = B.bID
结果如下:
aID aName bID bXuehao
1 a1 1 2006102401
2 a2 2 2006102402
3 a3 3 2006102403
4 a4 4 2006102404
(所影响的行数为 4 行)
结果是基于A表和B表的
- 面试之SQL(2)--left join, inner join 和 right join的区别
- 面试之SQL(2)--left join, inner join 和 right join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- Sql 之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- Sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- sql之left join、right join、inner join的区别
- 第12章 增加友情链接
- 面试之SQL(1)--选出选课数量>=2的学号
- UNIX环境编程 学习2
- iOS笔记之_OC面向对象语法2
- 工具集合笔记
- 面试之SQL(2)--left join, inner join 和 right join的区别
- 【PLSQL】过程procedure的形参和实参
- pl/sql 配置
- javascript原型链和继承
- 第13章 增加404页面
- libgdx 游戏走起
- 图解Windows下开发Objective-C程序之二 - Objective-C入门例子
- cocos2dx v3.x C++绑定lua
- BZOJ 1076 [SCOI 2008] 奖励关 (概率与期望)