sql - 如何将多列合并为一列？

Question

我正在编写一个查询并希望在一列中得到结果
我目前的结果是这样返回的

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而不是 UNION ALL .

您也可以使用 UNPIVOT 执行此操作运算符(operator)

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/