使用bigquery sql将列转换为行

CREATE TABLE new_table AS
SELECT 'column1' AS column_name, column1 AS column_value FROM my_table
UNION ALL
SELECT 'column2' AS column_name, column2 AS column_value FROM my_table
UNION ALL
SELECT 'column3' AS column_name, column3 AS column_value FROM my_table
...

SELECT t1.column_value AS column1, t2.column_value AS column2, t3.column_value AS column3, ...
FROM new_table t1
CROSS JOIN new_table t2
CROSS JOIN new_table t3
...
WHERE t1.column_name = 'column1'
AND t2.column_name = 'column2'
AND t3.column_name = 'column3'
...