Mysql联合不能对相同的值求和

SELECT column1, SUM(column2) AS sum_value
FROM table
GROUP BY column1
UNION
SELECT column1, SUM(column2) AS sum_value
FROM table
GROUP BY column1;

CREATE TEMPORARY TABLE temp_table
SELECT column1, SUM(column2) AS sum_value
FROM table
GROUP BY column1;

SELECT column1, sum_value
FROM temp_table
UNION
SELECT column1, sum_value
FROM temp_table;