使用聚合函数查找 MySQL 中列值的平均值

让我们首先创建一个表 -

mysql> create table DemoTable
(
   Number int
);
Query OK, 0 rows affected (0.79 sec)

使用插入命令在表中插入一些记录 -

mysql> insert into DemoTable values(56);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable values(78);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable values(89);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values(98);
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values(91);
Query OK, 1 row affected (0.35 sec)
mysql> insert into DemoTable values(96);
Query OK, 1 row affected (0.15 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 -

+--------+
| Number |
+--------+
|     56 |
|     78 |
|     89 |
|     98 |
|     91 |
|     96 |
+--------+
6 rows in set (0.00 sec)

以下是获得列值平均值的查询 -

mysql> select (sum(Number)*(100))/(100+500) from DemoTable;

这将产生以下输出 -

+-------------------------------+
| (sum(Number)*(100))/(100+500) |
+-------------------------------+
|                       84.6667 |
+-------------------------------+
1 row in set (0.00 sec)

更新于: 26-9-2019

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