Question

对于这样的事情有什么办法吗？：

SELECT * FROM table1
INNER JOIN table2
    ON table1.field = table2.field
WHERE field2 IN (SELECT * FROM table3 WHERE field LIKE '%pattern%')

更准确地说，在IN（）内部我需要table3行中与％pattern％匹配的值，因此我可以从主查询中获取具有field3 IN（）范围的table3值的行。

Answer 1

您应该只选择所需的字段，如

SELECT field2 FROM table3 WHERE field LIKE '%pattern%'

Answer 2

您可以这样做，但列的数量和类型必须匹配

SELECT * FROM table1
INNER JOIN table2
ON table1.field = table2.field
WHERE field2 IN (SELECT field3 FROM table3 WHERE field LIKE '%pattern%')

或者例如：

SELECT * FROM table1
INNER JOIN table2
ON table1.field = table2.field
WHERE (field2_1, field2_2) fi IN (SELECT field3_1, field3_2
                                 FROM table3 
                                 WHERE field LIKE '%pattern%')

（field2_1，field2_2）和field3_1，field3_2必须匹配数字和类型

Answer 3

您可以直接使用JOIN for table3：

代替子查询

SELECT *
FROM table1 T1
INNER JOIN table2 T2 ON T2.field = T1.field
INNER JOIN table3 T3 ON T3.field = T1.field2
WHERE T3.field LIKE '%pattern%'

此处T1，T2和T3为table alias以提高可读性

SELECT WHERE IN（子查询）

3 个答案: