如何将8个sql查询组合成一个结果集？

SELECT column1, column2 FROM table1
UNION
SELECT column1, column2 FROM table2
UNION
SELECT column1, column2 FROM table3
...

SELECT column1, column2 FROM table1
UNION ALL
SELECT column1, column2 FROM table2
UNION ALL
SELECT column1, column2 FROM table3
...

SELECT t1.column1, t2.column2
FROM (SELECT column1 FROM table1) AS t1
JOIN (SELECT column2 FROM table2) AS t2 ON t1.id = t2.id
...

CREATE TEMPORARY TABLE temp1 AS SELECT column1 FROM table1;
CREATE TEMPORARY TABLE temp2 AS SELECT column2 FROM table2;
...
SELECT t1.column1, t2.column2
FROM temp1 AS t1
JOIN temp2 AS t2 ON t1.id = t2.id
...