要了解AVG功能考虑EMPLOYEE_TBL表具有以下记录：
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mysql> SELECT * FROM employee_tbl;+------+------+------------+--------------------+| id | name | work_date | daily_typing_pages |+------+------+------------+--------------------+| 1 | John | 2007-01-24 | 250 || 2 | Ram | 2007-05-27 | 220 || 3 | Jack | 2007-05-06 | 170 || 3 | Jack | 2007-04-06 | 100 || 4 | Jill | 2007-04-06 | 220 || 5 | Zara | 2007-06-06 | 300 || 5 | Zara | 2007-02-06 | 350 |+------+------+------------+--------------------+7 rows in set (0.00 sec) |
现在，假设根据上面的表，要计算所有的dialy_typing_pages的平均值，那么可以通过使用下面的命令：
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mysql> SELECT AVG(daily_typing_pages) -> FROM employee_tbl;+-------------------------+| AVG(daily_typing_pages) |+-------------------------+| 230.0000 |+-------------------------+1 row in set (0.03 sec) |
可以把平均使用GROUP BY子句设置的各种记录。下面的例子将采取平均到一个人的所有相关的记录，每个人的平均页打印纸。
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mysql> SELECT name, AVG(daily_typing_pages) -> FROM employee_tbl GROUP BY name;+------+-------------------------+| name | AVG(daily_typing_pages) |+------+-------------------------+| Jack | 135.0000 || Jill | 220.0000 || John | 250.0000 || Ram | 220.0000 || Zara | 325.0000 |+------+-------------------------+5 rows in set (0.20 sec) |
