Question

是否可以对两个单独的INNER JOIN进行OR运算，以便结果集包含来自两个INNER JOIN的数据？例如，MySQL中有以下几种可能。

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

正如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

您需要使用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！

在MySQL中运行两个INNER JOIN

3 个答案: