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MySQL查询基于特定记录对值进行分组和求和

2024-05-19 04:42:06 389

使用GROUPBY对记录进行分组，而SUM()函数用于添加。让我们首先创建一个表-

create table DemoTable
(
   Name varchar(40),
   Subject varchar(40),
   Marks int
);

使用插入命令在表中插入一些记录-

insert into DemoTable values('Chris','MySQL',76);
insert into DemoTable values('Sam','MongoDB',86);
insert into DemoTable values('Mike','MySQL',98);
insert into DemoTable values('David','Java',93);
insert into DemoTable values('Bob','MySQL',57);
insert into DemoTable values('John','MongoDB',77);

使用select语句显示表中的所有记录-

select *from DemoTable;

这将产生以下输出-

+-------+---------+-------+
| Name  | Subject | Marks |
+-------+---------+-------+
| Chris | MySQL   |    76 |
| Sam   | MongoDB |    86 |
| Mike  | MySQL   |    98 |
| David | Java    |    93 |
| Bob   | MySQL   |    57 |
| John  | MongoDB |    77 |
+-------+---------+-------+
6 rows in set (0.00 sec)

以下是根据SUBJECT对值进行分组和求和的查询-

select Subject,SUM(Marks) from DemoTable group by Subject;

这将产生以下输出-

+---------+------------+
| Subject | SUM(Marks) |
+---------+------------+
| MySQL   |        231 |
| MongoDB |        163 |
| Java    |         93 |
+---------+------------+
3 rows in set (0.00 sec)

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MySQL查询基于特定记录对值进行分组和求和

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