一张图看懂 SQL 的各种 JOIN 用法

秋山信月归

03-24 25阅读

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

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list> 

FROM Table_A A

INNER JOIN Table_B B

ON A.Key = B.Key

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list>

FROM Table_A A

LEFT JOIN Table_B B

ON A.Key = B.Key

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list>

FROM Table_A A

RIGHT JOIN Table_B B

ON A.Key = B.Key

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list>

FROM Table_A A

FULL OUTER JOIN Table_B B

ON A.Key = B.Key

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list> 

FROM Table_A A

LEFT JOIN Table_B B

ON A.Key = B.Key

WHERE B.Key IS NULL

一张图看懂 SQL 的各种 JOIN 用法

SELECT <select_list>

FROM Table_A A

RIGHT JOIN Table_B B

ON A.Key = B.Key

WHERE A.Key IS NULL

一张图看懂 SQL 的各种 JOIN 用法

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