MySQL SUM()函數

MySQL SUM()函數用法實例代碼教學-MySQL的SUM函數是用來找出記錄中各種的字段的總和。

MySQL的SUM函數是用來找出記錄中各種的字段的總和。

要了解SUM函數考慮EMPLOYEE_TBL表具有以下記錄：

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)

現在，假設根據上麵的表想來計算所有的dialy_typing_pages的總數，那麼可以通過使用下麵的命令：

mysql> SELECT SUM(daily_typing_pages)
    -> FROM employee_tbl;
+-------------------------+
| SUM(daily_typing_pages) |
+-------------------------+
|                    1610 |
+-------------------------+
1 row in set (0.00 sec)

可以使用GROUP BY子句設置的各種記錄的總和。下麵的例子將總結所有相關的記錄一個人，打印紙的每一個人總數。

mysql> SELECT name, SUM(daily_typing_pages)
    -> FROM employee_tbl GROUP BY name;
+------+-------------------------+
| name | SUM(daily_typing_pages) |
+------+-------------------------+
| Jack |                     270 |
| Jill |                     220 |
| John |                     250 |
| Ram  |                     220 |
| Zara |                     650 |
+------+-------------------------+
5 rows in set (0.17 sec)