请帮助破解sql查询，以使用自连接或任何其他方式获取记录

我有一个Cust表，它有两列custid和flag。对于同一个custid，有一些记录带有标志u和I。 我只想获取只标记为U而不是I的记录。 例如：

客户表：

custid  flag
123      U
123      I
124      U
124      I
125      U
126      U
126      I
127      U
127      U

我想选择Custid125和127，因为他们没有国旗I

---

请建议查询。

如果您围绕您的

custid

分组，则只能选择不存在

标志='I'

的查询

select custid
from cust
group by custid
having count(case when flag = 'I' 
                  then 1 
                  else 0
             end) = 0

这是另一种方法。（）

将具有

标志的客户编号

作为

'I'

，如果

等于0

，则选择该

客户ID

select a.num, a.custid
from
(select count(flag) as num, custid
from cust
group by custid) as a
inner join 
(select count(flag) as num, custid
    from cust
    where flag = 'U'
    group by custid) as b
on a.custid = b.custid
and a.num = b.num

结果是：

select x.custId 
from cust x
      left join (select custId from cust where flag = 'I') y
      on x.custId = y.custId
where y.custId is null 
group by x.custId

select distinct custid from cust
MINUS
select distinct custid from cust where flag = 'I'

select distinct c.custid from cust c where (select count(*) 
from cust where custid = c.custid and flag = 'I') = 0

select a.num, a.custid
from
(select count(flag) as num, custid
from cust
group by custid) as a
inner join 
(select count(flag) as num, custid
    from cust
    where flag = 'U'
    group by custid) as b
on a.custid = b.custid
and a.num = b.num