SQL查询返回特定列的重复行，但另一列具有唯一值

Question

我编写了此处显示的查询，该查询组合了三个表并返回来自appeal_tickets 的at_ticket_num 重复但针对不同的at_sys_ref 值的行

select top 100 
    t.t_reference, at.at_system_ref, at_ticket_num, a.a_case_ref
from 
    tickets t, appeal_tickets at, appeals_2 a
where 
    t.t_reference in ('AB123','AB234') -- filtering on these values so that I can see that its working
    and t.t_number = at.at_ticket_num
    and at.at_system_ref = a.a_system_ref
    and at.at_ticket_num IN (select at_ticket_num
                             from appeal_tickets
                             group by at_ticket_num
                             having count(distinct at_system_ref) > 1)
order by 
    t.t_reference desc

这是输出：

t_reference  at_system_ref  at_ticket_num   a_case_ref
-------------------------------------------------------
    AB123       30838974      23641583      1111979010
    AB123       30838976      23641583      1111979010
    AB234       30839149      23641520      1111977352
    AB234       30839209      23641520      1111988003

我想对此进行修改，使其仅返回 t_reference 重复但针对不同 a_case_ref 的记录。所以在上述情况下，只会返回 AB234 的记录。

任何帮助将不胜感激。

Answer 1

您希望所有具有多个系统参考和多个案例参考的工单上诉似乎。您可以加入表格，计算每个工单的出现次数，然后只保留符合这些条件的工单。

select *
from
(
  select
    t.t_reference, at.at_system_ref, at.at_ticket_num, a.a_case_ref,
    count(distinct a.a_system_ref) over (partition by at.at_ticket_num) as sysrefs,
    count(distinct a.a_case_ref) over (partition by at.at_ticket_num) as caserefs
  from tickets t
  join appeal_tickets at on at.at_ticket_num = t.t_number
  join appeals_2 a on a.a_system_ref = at.at_system_ref
) counted
where sysrefs > 1 and caserefs > 1
order by t.t_reference, at.at_system_ref, at.at_ticket_num, a.a_case_ref;

更正

SQL Server 似乎还不支持COUNT(DISTINCT ...) OVER (...)。不过，您可以在子查询中计算不同的值。替换

count(distinct a.a_system_ref) over (partition by at.at_ticket_num) as sysrefs,

通过

(
  select count(distinct a2.a_system_ref)
  from appeal_tickets at2
  join appeals_2 a2 on a2.a_system_ref = at2.at_system_ref
  where at2.at_ticket_num = t.t_number
) as sysrefs,

另一种解决方法是在两个方向上使用DENSE_RANK（在此处找到：https://stackoverflow.com/a/53518204/2270762）：

dense_rank() over (partition by at.at_ticket_num order by a.a_system_ref) +
dense_rank() over (partition by at.at_ticket_num order by a.a_system_ref desc) - 
1 as sysrefs,

Answer 2

with data as (
    <your query plus one column>,
    case when
        min() over (partition by t.t_reference)
        <>
        max() over (partition by t.t_reference)
        then 1 end as dup
)
select * from data where dup = 1