在单个MySQL查询中根据条件执行SUM和SUBTRACTION？
为此，使用CASE语句并为SUM和SUBTRACTION设置。让我们首先创建一个表-
mysql> create table DemoTable866( Status varchar(100), Amount int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable866 values('ACTIVE',50);
mysql> insert into DemoTable866 values('INACTIVE',70);
mysql> insert into DemoTable866 values('INACTIVE',20);
mysql> insert into DemoTable866 values('ACTIVE',100);
mysql> insert into DemoTable866 values('ACTIVE',200);使用select语句显示表中的所有记录-
mysql> select *from DemoTable866;
这将产生以下输出-
+----------+--------+ | Status | Amount | +----------+--------+ | ACTIVE | 50 | | INACTIVE | 70 | | INACTIVE | 20 | | ACTIVE | 100 | | ACTIVE | 200 | +----------+--------+ 5 rows in set (0.00 sec)
以下是使用单个MySQL查询在同一列中执行SUM或SUBTRACTION的查询-
mysql> select sum(CASE WHEN Status = 'ACTIVE' then Amount WHEN Status = 'INACTIVE' then -Amount END) AS RemainingAmount from DemoTable866;
这将产生以下输出-
+-----------------+ | RemainingAmount | +-----------------+ | 260 | +-----------------+ 1 row in set (0.06 sec)