MySql某一列累计查询

问题：有一列数据，需要累计显示出来

比如：id salary 查询结果：id salary sumSalary

1 10000 1 10000 10000

　　2 20000 2 20000 30000

　　 3 30000 3 30000 60000

解决方案

1、使用自定义变量

　①用 Set 定义变量

mysql> set @sumSalary := 0;

mysql> select id,salary,(@sumSalary := @sumSalary + salary) as sum from tbl_stu order by id asc;

②不适用 Set 定义变量，使用 join

mysql> select id,salary,(@sumSalary := @sumSalary + salary) as sum from tbl_stu a join (select @sumSalary := 0) b order by id asc;

2、使用子查询

　　 mysql> select id,salary,(select sum(salary) from tbl_stu b where b.id <= a.id) sumSalary from tbl_stu a order by id asc;