Question

这是SQL Server CTE，尝试转换为Oracle CTE或常规oracle查询..

;with cte as 

(Select AC, M, Y, D, E, F, CD 

from tblA
WHere 

(Y = YEAR(GETDATE()) and M = Month(dateadd(month, -1, GETDATE()))) 

), 

cte2 as

(Select A.AC,Max(A.Y)as Y, Max(A.M) as M, Max(A.CD) as CD

from tbl A

Inner join cte B on B.AC = A.AC

WHere A.CD is Not Null and B.CD is Null

Group by A.AC)

, cte3 as

(Select C.AC, C.Y, C.M, C.D, C.E, C.F, C.CD

from tblA C

Inner join cte2 D on C.AC = D.AC and C.Y= D.Y and C.M = D.M and 

    D.CD = C.CD
) 
select * from cte

union

select * from cte3;

Answer 1

假设您的cte / cte3选择列表中没有有意颠倒m和y列，我认为您可以将查询重写为：

with cte1 as (select a.ac,
                     a.m,
                     a.y,
                     a.d,
                     a.e,
                     a.f,
                     a.cd,
                     max(case when a.cd is not null and b.cd is not null then a.y end) over (partition by a.ac) max_y,
                     max(case when a.cd is not null and b.cd is not null then a.m end) over (partition by a.ac) max_m,
                     max(case when a.cd is not null and b.cd is not null then a.cd end) over (partition by a.ac) max_cd
              from   tbla a
                     left outer join tblb b on (a.ac = b.ac))
select ac,
       m,
       y,
       d,
       e,
       f,
       cd
from   cte1
where  (y = to_char(sysdate, 'yyyy')
        and m = to_char(add_months(sysdate, -1), 'mm'))
or     (y = max_y
        and m = max_m
        and cd = max_cd);

您尚未提供任何示例数据，因此我无法测试，但是值得将日期函数转换为其SQL Server等效项并进行测试以确保返回的数据相同。

这样，您不会在同一个表中查询3次，这样可以提高性能。

将SQL Server CTE转换为Oracle CTE

1 个答案: