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MySQL查询以查找具有相同ID的行的平均值

2024-04-25 10:01:04 390

让我们首先创建一个表-

mysql> create table DemoTable
(
   StudentId int,
   StudentMarks int
);

使用插入命令在表中插入一些记录-

mysql> insert into DemoTable values(1000,78);
mysql> insert into DemoTable values(1001,88);
mysql> insert into DemoTable values(1000,89);
mysql> insert into DemoTable values(1000,67);
mysql> insert into DemoTable values(1000,90);
mysql> insert into DemoTable values(1001,91);

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-

+-----------+--------------+
| StudentId | StudentMarks |
+-----------+--------------+
|      1000 |           78 |
|      1001 |           88 |
|      1000 |           89 |
|      1000 |           67 |
|      1000 |           90 |
|      1001 |           91 |
+-----------+--------------+
6 rows in set (0.00 sec)

以下是查询以查找具有相同ID的行的平均值-

mysql> select StudentId,avg(StudentMarks) from DemoTable group by StudentId;

这将产生以下输出-

+-----------+-------------------+
| StudentId | avg(StudentMarks) |
+-----------+-------------------+
|      1000 |           81.0000 |
|      1001 |           89.5000 |
+-----------+-------------------+
2 rows in set (0.03 sec)

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MySQL查询以查找具有相同ID的行的平均值

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