MySql学习之Join查询

梦幻逝水 2017-08-25 15:51

本文章为尚硅谷教学视频总结，仅供学习及参考。如有侵权请及时告知。

1、SQL执行顺序

（1）手写sql顺序

（2）机读sql顺序

2、7种Join的sql编写

注：图中 full outer join在MySQL中是不支持的。可通过

(1)全有

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

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