如何检索组中缺少的记录

Question

我正在尝试使用SQL从以下数据集中检索记录。对于POKey和PAKey的每种组合，我都试图查找是否存在RCode 9和RCode 10，而缺少RCode 8。

我已附上示例数据，请帮助我了解如何操作。

Answer 1

这是您想要的吗？

select PoKey, PaKey, 'Missing 8'
from t
group by PoKey, PaKey
having sum(case when rcode = 9 then 1 else 0 end) > 0 and
       sum(case when rcode = 10 then 1 else 0 end) > 0 and
       sum(case when rcode = 8 then 1 else 0 end) = 0;

Answer 2

我会使用NOT EXISTS：

select distinct t.PoKey, t.PaKey, 'Missing 8' as Rcode
from table t
where RCode in (9, 10) and
      not exists (select 1 
                  from table t1 
                  where t1.PoKey = t.PoKey and 
                        t1.PaKey = t.PaKey and 
                        t1.Rcode = 8
                 );