SUM函数返回的一个表达式总的值,这个函数也是非常有用的,下面我们来看看这个函数用详细用法吧
SUM函数的语法是:
代码如下 | 复制代码 |
SELECT SUM(expression ) |
表达式可以是一个数值字段或公式。
简单的例子
例如,你可能想知道合并全体员工的薪金总额美元以上,其薪酬是25,000/年
代码如下 | 复制代码 |
SELECT SUM(salary) as "Total Salary" |
与Example using DISTINCT一起用
代码如下 | 复制代码 |
SELECT SUM(DISTINCT salary) as "Total Salary" |
使用公式的示例
在SUM函数中的表达并不需要一个单一的领域。您也可以使用一个公式。例如,您可能需要为业务的净收入。总收入减去总支出纯收入计算。
代码如下 | 复制代码 |
SELECT SUM(income - expenses) as "Net Income" |
您可能还需要在SUM函数执行数学运算。例如,您可能会确定佣金总额为销售总额的10%。
代码如下 | 复制代码 |
SELECT SUM(sales * 0.10) as "Commission" |
与Example using GROUP BY
在某些情况下,你将被要求使用SUM函数的第一个集团。
例如,您还可以使用SUM函数返回的部门名称和总销售额(相关部门)。
代码如下 | 复制代码 |
SELECT department, SUM(sales) as "Total sales" |

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