如何使用 MySQL SUM() 函数?
mysqlmysqli database更新于 2024/3/14 8:13:00
MySQL SUM 函数用于找出各种记录中某个字段的总和。要理解 SUM() 函数，请考虑一个"employee_tbl"表，该表包含以下记录 −
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，假设您想要根据上表计算所有 dialy_typing_pages 的总数，那么您可以使用以下命令进行计算 −
mysql> SELECT SUM(daily_typing_pages) -> FROM employee_tbl; +-------------------------+ | SUM(daily_typing_pages) | +-------------------------+ | 1610 | +-------------------------+ 1 row in set (0.00 sec)
