Question

如何在不使用from子句中的子查询的情况下加入这两个选择？

SELECT 0 a UNION SELECT 1 a UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9;

SELECT 0 b UNION SELECT 10 UNION SELECT 20 UNION SELECT 30 UNION SELECT 40 UNION SELECT 50 UNION SELECT 60 UNION SELECT 70 UNION SELECT 80 UNION SELECT 90;

结果应为100行：

每一个（0,1,2,3,4,5,6,7,8,9）加入每个b（0,10,20,30,40,50,60,70,80,90））

我需要这个，因为如果from子句中有子查询，我就无法创建视图......

谢谢！

Answer 1

使用CROSS JOIN

SELECT 
*
FROM 
( SELECT 0 a UNION SELECT 1 a UNION SELECT 2 UNION SELECT 3
    UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7
    UNION SELECT 8 UNION SELECT 9 ) AS A


CROSS JOIN

(
 SELECT 0 b UNION SELECT 10 UNION SELECT 20 
    UNION SELECT 30 UNION SELECT 40 UNION SELECT 50 UNION SELECT 60
     UNION SELECT 70 UNION SELECT 80 UNION SELECT 90
) AS B

注意：

如果表格A有n行，而表格B有m行，那么

A CROSS B将有m * n行

MySql在from子句中连接两个没有子查询的select语句

1 个答案: