如何将多列合并为一列？

Question

我正在编写一个查询并希望将结果放在一列中我当前的结果返回这样

Column1     Column2    column3
1              A         CAT

我希望结果像这样返回

Column1
1
A
CAT

Answer 1

SELECT Column1 FROM TableName
UNION ALL
SELECT Column2 FROM TableName
UNION ALL
SELECT Column3 FROM TableName

如果您不想要重复的值，请使用UNION代替UNION ALL。

您也可以使用UNPIVOT运算符执行此操作

SELECT Column123
FROM
(
  SELECT Column1, Column2, Column3 
  FROM TableName
) AS tmp
UNPIVOT 
(
  Column123 FOR ColumnAll IN (Column1, Column2, Column3)
) AS unpvt;

https://www.w3schools.com/sql/sql_union.asp
https://www.mssqltips.com/sqlservertip/3000/use-sql-servers-unpivot-operator-to-help-normalize-output/