mysql - 从表中删除数据时出现错误 #1242

Question

我正在尝试从表中删除数据，我的查询如下：

delete from mybadge where uid=5 and badge_name=(select concat(tag_name,'-Beginner') from tag,post_tags where post_tags.tag_id=tag.tag_id);

我通过 select 语句获得 5 条记录，我想删除所有 5 条记录。

Answer 1

使用 - 'in'关键字而不是'='符号

delete from mybadge where uid=5 and badge_name in (select concat(tag_name,'-Beginner') from tag,post_tags where post_tags.tag_id=tag.tag_id);

Answer 2

正如您所说，您的子查询返回 5 行。但是，badge_name 在同一行中不能有 5 个不同的值。这有点像说：

 delete from mybadge where uid=5 and badge_name=(5 different values)

尝试

delete from mybadge where uid=5 and badge_name in (select concat(tag_name,'-Beginner') from tag,post_tags where post_tags.tag_id=tag.tag_id);

Answer 3

如果 select 语句对您来说工作正常，那么只需删除 select 返回的所有 uid：

DELETE FROM mybadge WHERE uid IN(
SELECT uid
FROM mybadge 
WHERE uid=5 
AND badge_name=(SELECT concat(tag_name,'-Beginner') 
                FROM tag,post_tags 
                WHERE post_tags.tag_id=tag.tag_id)
);