如何在MySQL中在满足另一列条件的情况下对列中的单元格求和？

为此，您可以使用聚合函数SUM（）和GROUP BY子句。让我们首先创建一个表 –

mysql> create table DemoTable
   -> (
   -> EmployeeName varchar(20),
   -> JoiningDate date,
   -> Salary int
   -> );
Query OK, 0 rows affected (0.54 sec)

使用插入命令在表中插入一些记录 –

mysql> insert into DemoTable values('David','2019-11-02',400);
Query OK, 1 row affected (0.52 sec)
mysql> insert into DemoTable values('Robert','2018-11-25',100);
Query OK, 1 row affected (0.39 sec)
mysql> insert into DemoTable values('Bob','2019-12-14',600);
Query OK, 1 row affected (0.25 sec)
mysql> insert into DemoTable values('Carol','2019-11-03',300);
Query OK, 1 row affected (0.23 sec)

使用select语句显示表中的所有记录 –

mysql> select * from DemoTable;

这将产生以下输出 –

+--------------+-------------+--------+
| EmployeeName | JoiningDate | Salary |
+--------------+-------------+--------+
| David        | 2019-11-02  |    400 |
| Robert       | 2018-11-25  |    100 |
| Bob          | 2019-12-14  |    600 |
| Carol        | 2019-11-03  |    300 |
+--------------+-------------+--------+
4 rows in set (0.00 sec)

这是在另一列中满足条件时对列中的单元格求和的查询 –

mysql> select year(JoiningDate) as JoiningYear,
   -> month(JoiningDate) as JoiningMonth,
   -> sum(Salary) as Total,
   -> group_concat(EmployeeName) as Name
   -> from DemoTable
   -> group by JoiningYear,JoiningMonth;

这将产生以下输出 –

+-------------+--------------+-------+-------------+
| JoiningYear | JoiningMonth | Total | Name        |
+-------------+--------------+-------+-------------+
|        2018 |           11 |   100 | Robert      |
|        2019 |           11 |   700 | David,Carol |
|        2019 |           12 |   600 | Bob         |
+-------------+--------------+-------+-------------+
3 rows in set (0.04 sec)

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