通过将 MySQL SUM() 函数与 HAVING 子句结合使用，它会根据 HAVING 子句后给出的特定条件过滤结果。要理解上述概念，请考虑一个“employee_tbl”表，该表具有以下记录 -
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，下面的查询将使用 HAVING 子句和 SUM() 函数来获取超过 250 的 daily_typing_pages 总数。
mysql> Select Name, SUM(daily_typing_pages) From employee_tbl GROUP BY NAME HAVING SUM(daily_typing_pages) > 250; +------+-------------------------+ | name | SUM(daily_typing_pages) | +------+-------------------------+ | Jack | 270 | | Zara | 650 | +------+-------------------------+ 2 rows in set (0.17 sec)
