SUM() 函数
SUM() 函数返回数值列的总数。
SQL SUM() 语法
SELECT SUM(column_name) FROM table_name;
演示数据库
在猿变手册教程中，我们将使用 yuanbian 样本数据库。
下面是选自 "ordes" 表的数据：
+----------+--------------+----------+--------------+----------------+---------------------+
| order_id | order_no | goods_id | order_amount | order_quantity | create_date |
+----------+--------------+----------+--------------+----------------+---------------------+
| 1 | 201503120001 | 10 | 1000 | 10 | 2015-03-12 09:00:04 |
| 2 | 201503120002 | 12 | 1300 | 12 | 2015-03-12 17:23:10 |
| 3 | 201503130001 | 11 | 2400 | 22 | 2015-03-13 10:30:12 |
| 4 | 201503130002 | 12 | 2500 | 15 | 2015-03-13 11:00:05 |
| 5 | 201503130003 | 10 | 1400 | 15 | 2015-03-13 14:54:00 |
| 6 | 201503140001 | 12 | 2100 | 12 | 2015-03-14 11:34:00 |
+----------+--------------+----------+--------------+----------------+---------------------+
SQL SUM() 示例
下面的 SQL 语句查找 "orders" 表的 "order_amount" 字段的总数,即订单总额：
SELECT SUM(order_amount) AS total_amount
FROM orders;执行以上 SQL 输出结果如下：
+--------------+
| total_amount |
+--------------+
| 10700 |
+--------------+
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