Question

我有2张桌子。

我使用此查询来查找另一个表中一个表的字段出现次数

select t.id, t.tag_text, count(*) cnt from sms s, template as t
where s.id_template=t.id
group by  t.tag_text
order by  cnt desc

如果在短信中出现的行少于5次，如何从模板中删除所有行？这意味着如果count小于5.我使用MySQL。

Answer 1

您可以使用过滤器聚合结果，例如：

  select t.id, t.tag_text, count(*) cnt 
  from sms s, template as t
  where s.id_template=t.id
  group by  t.tag_text
  having count(*) <5 
  order by  cnt desc

并删除例如：

  delete from  
  from sms as s
  inner join template as t on s.id_template=t.id
  group by  t.tag_text
  having count(*) <5

Answer 2

delete from template 

where   id in
        (
            select      id_template
            from        sms
            group by    id_template
            having      count(*) < 5 
        )

如何从一个表中删除少于？

2 个答案: