mysql将列转换为行

我有一个视图是从多个表中创建的视图结构是

id     col1     col2     col3     col4

101     A     B     B     NULL

102     C     F     A     G

等等（这是示例）

我想创建另一个看起来像

ID     col_name     value

101     col1     A

101     col2     B

101     col3     B

101     col4     NULL

102     col1     C

102     col2     F

102     col3     A

102     col4     G

等等

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有人能帮上忙吗？也许是这样的：

CREATE VIEW foo
AS
SELECT id, 'col1' AS col_name, col1 as `Value`
UNION ALL
SELECT id, 'col2', col2
UNION ALL
SELECT id, 'col3', col3
UNION ALL
SELECT id, 'col4', col4;

SELECT id,'col1' AS colName, col1 AS value FROM table1
UNION ALL
SELECT id,'col2' AS colName, col2 AS value FROM table1
UNION ALL
SELECT id,'col3' AS colName, col3 AS value FROM table1
UNION ALL
SELECT id,'col4' AS colName, col4 AS value FROM table1

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编写新视图直接从多个表获取信息怎么样？