Question

我想删除以下子查询的结果。我怎么做？

delete
from mytable
where rowid in (select rowid, count(*) as count from mytable group by mygroup having count > 50)

不起作用：

[1] [SQLITE_ERROR] SQL错误或缺少数据库（子选择返回8 栏-预期1）

Answer 1

delete
from mytable
where rowid in (select rowid from (select rowid, count(*) as count from mytable group by mygroup having count > 50))

Answer 2

我猜您在使用聚合函数时可能需要这样做，您需要在group by中添加非聚合列

delete
from mytable
where mygroup in (select mygroup from mytable group by mygroup having count(*) > 50)

Answer 3

如果选中此page，您会注意到，在使用IN和子查询时：

值列表是固定值列表或子查询返回的结果一列。返回的表达式类型和列表中的值必须相同。

您在这里的错误是您的子查询返回的列超过1（行和计数）。

要解决此问题，您可以尝试以下操作：

delete
from  mytable
where rowid in (select rowid 
                from (select rowid, 
                             count(*) as count 
                      from mytable 
                      group by mygroup 
                      having count > 50)
                )

请注意，假设您要删除所有mygroup计数大于50的结果，此查询将无法完成全部工作。它只会返回该组的一行。您应该尝试这样做：

select * FROM mytable
where mygroup in (select mygroup 
                  from (select mygroup,
                               count(*) as count
                        from mytable
                        group by mygroup
                        having count > 1)
                  );

如D-Shish's answer中所述。

这里是demo，用于查看这两个查询的两个不同结果集。

删除子查询中的结果

3 个答案: