一张图看懂 SQL 的各种 join 用法

2022-06-29 11:05:23

摘自

作者:C.L. Moffatt

http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

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

  • 作者:小毛睿耶巴蒂
  • 原文链接:https://blog.csdn.net/weixin_42655645/article/details/87620455
    更新时间:2022-06-29 11:05:23