问一个查询一对多的问题 一个表A,其中主要有id,ac_id,content列,ac_id是外键,content是记录,一个外键可以对应一个或过个记录,我想查找有2个以上记录的ac_id,怎么写tsql语句?我试了几个都不行。汗。烦请大家指教。 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 假如ac_id是B表的一个字段select A.*from Ainner join (select count(*) as num ,ac_id from B group by ac_id having count(*)>=2) Bon A.ac_id=B.ac_id select * from 表A where id in(select id from 表a where count(distinct ac_id)>=2 group by id) SELECT AC_ID , COUNT(DISTINCT CONTENT)CONTENT FROM A WHERE GROUP BY AC_ID HAVING COUNT(DISTINCT CONTENT)>2这样?? select * from A where acid in (select acid from B group by acid having count(*)>2) SQL codeSELECT AC_ID , COUNT(CONTENT)CONTENT FROM A WHERE GROUP BY AC_ID HAVING COUNT(CONTENT)>2去掉DISTINCT 我试了,4楼是正确的,看来关键是group by 和having的用法 sqlserver2000绿色版怎么连接不了?? select 语句中||是什么意思? 为了赋值,我select两次。第一次select是确认是否存在。这样效率是否可以改进? 求一条sql语句 求一sql语句:如何判断某一列是否在表中已经存在! 字符串串联的问题,似乎很简单,但一直未解决,请高手进来一看! 请问纪录级的权限怎样控制?谢谢了 兄弟们,我来提个问题,关于链接服务器的,很简单的 SQL Server 派生列的问题 做MIS,PowerBuilder好用,还是Delphi/C++Builder好用? 请求高手帮帮忙!!!!!!!!!!!!!!!! 函数的应用及写法问题
select A.*
from A
inner join (select count(*) as num ,ac_id from B group by ac_id having count(*)>=2) B
on A.ac_id=B.ac_id
select * from 表A where id in(select id from 表a where count(distinct ac_id)>=2 group by id)
AC_ID ,
COUNT(DISTINCT CONTENT)CONTENT
FROM
A
WHERE GROUP BY AC_ID HAVING COUNT(DISTINCT CONTENT)>2
这样??
SQL code
SELECT
AC_ID ,
COUNT(CONTENT)CONTENT
FROM
A
WHERE GROUP BY AC_ID HAVING COUNT(CONTENT)>2
去掉DISTINCT