mysql求1到100的偶数和

你可以使用以下 SQL 语句来求 1 到 100 的偶数和： SELECT SUM(num) FROM ( SELECT CASE WHEN MOD(n, 2) = 0 THEN n ELSE 0 END AS num FROM (SELECT @n := @n + 1 AS n FROM (SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) a, (SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) b, (SELECT 0 UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3) c, (SELECT @n := 0) d WHERE @n < 100 这个 SQL 语句使用了一个嵌套的 SELECT [子[查询](https://geek.csdn.net/educolumn/52858a23fd7979423d613db72f18dba0?spm=1055.2569.3001.10083)](https://geek.csdn.net/educolumn/251a67ccf9d4317480902b30e2a89676?spm=1055.2569.3001.10083)，其中使用了 CASE WHEN 语句来[判断](https://geek.csdn.net/educolumn/598ee2e4d0090de966a6f73039c4643b?spm=1055.2569.3001.10083)每个数是不是偶数，如果是偶数则返回该数，否则返回 0。外部的 SELECT [子[查询](https://geek.csdn.net/educolumn/52858a23fd7979423d613db72f18dba0?spm=1055.2569.3001.10083)](https://geek.csdn.net/educolumn/251a67ccf9d4317480902b30e2a89676?spm=1055.2569.3001.10083)则对返回的所有数求和，从而得到偶数的和。