sql-server - 如何从 2 列的 UNION 中获取 TOP 1 值？

Question

这是查询，如何从结果中选择前 1 个？这是针对 SQL Server 的。

SELECT column1 
FROM table 
WHERE column2 = 'Whatever' AND column3 = 'Sure'

UNION

SELECT column4 
FROM table 
WHERE column2 = 'Whatever' AND column3 = 'Sure'

Answer 1

尝试这个：

SELECT TOP 1 * FROM
(
  SELECT column1 FROM table WHERE column2 = 'Whatever' AND column3 = 'Sure'
  UNION
  SELECT column4 FROM table WHERE column2 = 'Whatever' AND column3 = 'Sure'
) R
ORDER BY Column1

Answer 2

尝试：

SELECT max(Column) FROM (
  SELECT column1 as Column FROM table WHERE ....
  UNION 
  SELECT column4 as Column FROM table WHERE ....
)

Answer 3

你的意思是

SELECT TOP 1 * 
FROM (
    SELECT column1 FROM table WHERE column2 = 'Whatever' AND column3 = 'Sure'
    UNION
    SELECT column4 FROM table WHERE column2 = 'Whatever' AND column3 = 'Sure')