mysql - 编写此 MySQL 查询 (JOIN) 的更好方法

Question

DELETE FROM table1
WHERE field1=(SELECT id FROM table2 WHERE type=1) 
OR field2=(SELECT id FROM table2 WHERE type=1)

编写此查询的正确方法是什么？它目前不起作用，因为子查询返回不止一行。

Answer 1

使用IN：

DELETE FROM table1
WHERE field1 IN (SELECT id FROM table2 WHERE type=1) 
OR field2 IN(SELECT id FROM table2 WHERE type=1)

Answer 2

你可以这样做IN：

delete
from table1
where field1 in (
        select id
        from table2
        where type = 1
        )
    or field2 in (
        select id
        from table2
        where type = 1
        )

Answer 3

根据您的桌子的大小，您可能能够摆脱 IN 方法。如果它们在较大的一侧，您可以使用 DELETE...USING 语法。

DELETE FROM foo USING foo, bar WHERE foo.field1=bar.id OR foo.field2=bar.id