在MySQL中求和对应的重复记录
让我们首先创建一个表-
mysql> create table DemoTable-> (
-> StudentName varchar(20),
-> StudentMarks int
-> );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values('Chris',50);mysql> insert into DemoTable values('David',70);
mysql> insert into DemoTable values('Chris',80);
mysql> insert into DemoTable values('David',90);
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-
+-------------+--------------+| StudentName | StudentMarks |
+-------------+--------------+
| Chris | 50 |
| David | 70 |
| Chris | 80 |
| David | 90 |
+-------------+--------------+
4 rows in set (0.00 sec)
这是对相应重复记录进行求和的查询，即学生的分数-
mysql> select StudentName,sum(StudentMarks) from DemoTable group by StudentName;
这将产生以下输出-
+-------------+-------------------+| StudentName | sum(StudentMarks) |
+-------------+-------------------+
| Chris | 130 |
| David | 160 |
+-------------+-------------------+
2 rows in set (0.00 sec)
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