Select UNION ALL 的最大记录数

Question

我有以下正确带回 3 组结果

SELECT        TOP (1) rid,score, weight
FROM            dbo.tblThree
WHERE        (caseNo = '111111111')
ORDER BY rID DESC

SELECT        TOP (1) rid,score, weight
FROM            dbo.tblTwo
WHERE        (caseNo = '111111111')
ORDER BY rID DESC

SELECT        TOP (1) rid,score, weight
FROM            dbo.tblOne
WHERE        (caseNo = '111111111')
ORDER BY rID DESC

由于 ORDER BY 语句，在它们之间添加 UNION ALL 失败。但是，如果我摆脱它们，它就会失败，因为它没有获得最新记录。

是否有更简单的解决方案？我想要的是一个 SQL 语句来输出 3 行。

Answer 1

尝试以下操作：

select * from ( select top (1) rid, score, weight
                from dbo.tblThree
                where caseNo = '111111111'
                order by rid desc) t1
union all
select * from ( select top (1) rid, score, weight
                from dbo.tblTwo
                where caseNo = '111111111'
                order by rid desc) t2
union all
select * from ( select top (1) rid, score, weight
                from dbo.tblOne
                where caseNo = '111111111' 
                order by rid desc) t3

Answer 2

试试这个查询

select rID,score, weight from 
(SELECT        TOP (1) rID,score, weight,ROW_NUMBER() over(order by rID) as a
FROM            dbo.tblThree
WHERE        (caseNo = '111111111')
UNION ALL
SELECT        TOP (1) rid,score, weight,ROW_NUMBER() over(order by rID) as a
FROM            dbo.tblTwo
WHERE        (caseNo = '111111111')
UNION ALL
SELECT        TOP (1) rid,score, weight,ROW_NUMBER() over(order by rID) as a
FROM            dbo.tblOne
WHERE        (caseNo = '111111111'))t

Answer 3

您可以使用以下方法获得所需的输出：

WITH data AS (
    SELECT        rid,score, weight, ROW_NUMBER() OVER (ORDER BY rID DESC) AS rn
    FROM            dbo.tblThree
    WHERE        (caseNo = '111111111')
    UNION ALL 
    SELECT        rid,score, weight, ROW_NUMBER() OVER (ORDER BY rID DESC) AS rn
    FROM            dbo.tblTwo
    WHERE        (caseNo = '111111111')
    UNION ALL
    SELECT        rid,score, weight, ROW_NUMBER() OVER (ORDER BY rID DESC) AS rn
    FROM            dbo.tblOne
    WHERE        (caseNo = '111111111')
)
SELECT *
FROM    data 
WHERE   rn = 1

Answer 4

;WITH CTE1 as
(
  SELECT        TOP (1) rid,score, weight
  FROM            dbo.tblThree
  WHERE        (caseNo = '111111111')
  ORDER BY rID DESC
), CTE2 as
(
  SELECT        TOP (1) rid,score, weight
  FROM            dbo.tblTwo
  WHERE        (caseNo = '111111111')
  ORDER BY rID DESC
), CTE3 as
(
  SELECT        TOP (1) rid,score, weight
  FROM            dbo.tblOne
  WHERE        (caseNo = '111111111')
  ORDER BY rID DESC
)
SELECT
  rid,score, weight 
FROM CTE1
UNION ALL
SELECT
  rid,score, weight 
FROM CTE2
UNION ALL
SELECT
  rid,score, weight 
FROM CTE3

Select UNION ALL 的最大记录数

Select Max Records on UNION ALL

sql

tsql

sql-server

sql-server-2008-r2

union-all