我可以從其他表中選擇一行嗎？

Question

說我有2個表「A」和「B」，我的查詢如下。

Select 
count(a."col_A1") as ACount, 
Sum(a."col_A2") as ASum, 
(Select count(b."col_B1") from B b) as BCount 
From A a 

我不能夠執行上面的Oracle語句，但它在MSSQL工作正常。

任何人都可以幫助我嗎？

Answer 1

只需在查詢的末尾添加一個GROUP BY 1即可。

Select count(a."col_A1") as ACount 
,  sum(a."col_A2") as ASum 
,  (Select count(b."col_B1") from B b) as BCount 
From A a 
GROUP BY 1 

Answer 2

這是一個有效的結構，包括在聚集結果的子查詢，但它看起來奇怪我。

我構建它：

select 
    a.c_col1, 
    a.s_col2, 
    b.c_col3 
from 
    (select count(col1) c_col1, 
      sum(col2) s_col2 
    from table_a) a, 
    (select count(col3) c_col3 
    from table_b) b