在 MySQL 中对两个 INNER JOIN 进行或运算

Question

是否可以对两个单独的 INNER JOIN 进行 OR 操作，以便结果集包含来自两个 INNER JOIN 中任一个的数据？例如，在 MySQL.

中是否可能出现以下情况

SELECT * FROM table1
(INNER JOIN table2 ON table1.column_name=table2.column_name)
OR
(INNER JOIN table3 ON table1.column_name=table3.column_name)

Answer 1

不，你不能这样做，一种方法是使用 union

SELECT * FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name
union
SELECT * FROM table1 INNER JOIN table3 ON table1.column_name=table3.column_name

Answer 2

您可以使用 UNION:

SELECT * FROM table1 INNER JOIN table2 ON table1.column_name=table2.column_name
UNION DISTINCT
SELECT * FROM table1 INNER JOIN table3 ON table1.column_name=table3.column_name

如 at https://dev.mysql.com/doc/refman/4.1/en/union.html 所述，UNION 结合了多个选择的结果。

Answer 3

你需要使用where

 select * from table1 
where

  (table1.column_name = (select table2.column_name from table2 inner join table1.column_name as  on table1.column_name = table2.column_name)) 

OR

  (table1.column_name = (select table3.column_name from table3   inner join table1.column_name as  on table1.column_name = table3.column_name))

在这里工作完美！

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