Question

我有两个表：TITLE和BACKGROUND

后台有一个外键进入TITLE所以我正在尝试编写一个查询，它将返回任何具有多个匹配BACKGROUND的TITLE行。

SELECT T.ID
  FROM TITLE T, BACKGROUND B
 WHERE T.ID = B.TITLE_ID
   AND /* there are multiple matching background rows */

Answer 1

select t.id
  from title t
 where exists (select * 
                 from background b
                where b.title_id = t.id
                having count(*) > 1 )

Answer 2

你试过.....

select T.ID from (
    SELECT T.ID,B.TITLE_ID, count(*)
      FROM TITLE T, BACKGROUND B
      WHERE T.ID = B.TITLE_ID
      group by T.ID,B.TITLE_ID
      having count(*) > 1
)

where子句中的聚合函数

2 个答案: