Question

我有一系列由union加入的查询。例如：

SELECT
    SUM(WHOS) [CRITERIA]
FROM ONFIRST

UNION

SELECT
    COUNT(WHATS) [CRITERIA]
FROM ONSECOND

UNION

SELECT
   IDONTKNOW [CRITERIA]
FROM ONTHIRD

等

查询结果并不总是以相同的顺序返回，我希望结果与我编写查询的顺序相同。

示例：有时我首先获得WHOS的SUM，有时我首先获得COUNT的数量。

实现这一目标的最佳方式是什么？

Answer 1

您可以使用虚拟订单列轻松控制此操作，并按该值排序：

;With Cte As 
(
    Select  Sum(WHOS) CRITERIA
          , 1 As Ord
    From    ONFIRST
    Union
    Select  Count(WHATS) CRITERIA
          , 2 As Ord
    From    ONSECOND
    Union
    Select  IDONTKNOW CRITERIA
          , 3 As Ord
    From    ONTHIRD
)
Select  CRITERIA
From    Cte
Order By Ord Asc;

如何控制联合查询中的执行顺序？

1 个答案: