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MySql学习之Join查询

数据库MysqlJoin查询
person smallyoungcalendar_today 2017年8月25日

一、SQL执行顺序 ​

1、手写sql顺序 ​

手写sql顺序

2、机读sql顺序 ​

机读sql顺序

机读sql顺序

二、7种Join的sql编写 ​

7种 SQL Joins

注：图中 full outer join在mysql中是不支持的。可通过

1、全有 ​

sql
SELECT <select_list> FROM TableA A LEFT JOIN TableB B ON A.Key = B.Key
UNION
SELECT <select_list> FROM TableA A RIGHT JOIN TableB B ON A.Key = B.Key

2、A的独有和B的独有 ​

sql
SELECT <select_list> FROM TableA A LEFT JOIN TableB B ON A.Key = B.Key WHERE B.Key IS NULL
UNION
SELECT <select_list> FROM TableA A RIGHT JOIN TableB B ON A.Key = B.Key WHERE A.Key IS NULL