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

看一张图秒懂 SQL 的各种 join 用法_内连接


具体分解如下：

1.INNER JOIN（内连接）

看一张图秒懂 SQL 的各种 join 用法_内连接_02



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


2.LEFT JOIN（左连接）

看一张图秒懂 SQL 的各种 join 用法_右连接_03



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


3.RIGHT JOIN（右连接）

看一张图秒懂 SQL 的各种 join 用法_右连接_04



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


4.OUTER JOIN（外连接）

看一张图秒懂 SQL 的各种 join 用法_外连接_05



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）

看一张图秒懂 SQL 的各种 join 用法_外连接_06



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）

看一张图秒懂 SQL 的各种 join 用法_内连接_07



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）

看一张图秒懂 SQL 的各种 join 用法_内连接_08



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


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  • SQL