sql left join用法_一张图看懂 SQL 的各种 join 用法

本文作者：C.L. Moffatt

下图展示了 LEFT JOIN、RIGHT JOIN、INNER JOIN、OUTER JOIN 相关的 7 种用法。

具体分解如下：

1.INNER JOIN（内连接）

SELECT <select_list> FROM Table_A A INNER JOIN Table_B B ON A.Key = B.Key

2.LEFT JOIN（左连接）

SELECT <select_list> FROM Table_A A LEFT JOIN Table_B B ON A.Key = B.Key

3.RIGHT JOIN（右连接）

SELECT <select_list> FROM Table_A A RIGHT JOIN Table_B B ON A.Key = B.Key

4.OUTER JOIN（外连接）

SELECT <select_list> FROM Table_A A FULL OUTER JOIN Table_B B ON A.Key = B.Key

5.LEFT JOIN EXCLUDING INNER JOIN（左连接-内连接）

SELECT <select_list> FROM Table_A A LEFT JOIN Table_B B ON A.Key = B.Key WHERE B.Key IS NULL

6.RIGHT JOIN EXCLUDING INNER JOIN（右连接-内连接）

SELECT <select_list> FROM Table_A A RIGHT JOIN Table_B B ON A.Key = B.Key WHERE A.Key IS NULL

7.OUTER JOIN EXCLUDING INNER JOIN（外连接-内连接）

SELECT <select_list> FROM Table_A A FULL OUTER JOIN Table_B B ON A.Key = B.Key WHERE A.Key IS NULL OR B.Key IS NULL

总结

以上是生活随笔为你收集整理的sql left join用法_一张图看懂 SQL 的各种 join 用法的全部内容，希望文章能够帮你解决所遇到的问题。

如果觉得生活随笔网站内容还不错，欢迎将生活随笔推荐给好友。