SQLite SUM()函数用于返回表达式或给定数字列的总和。

语法

SELECT SUM(aggregate_expression)  
FROM tables  
[WHERE conditions];

在SUM()函数中使用GROUP BY子句时的语法：

SELECT expression1, expression2, ... expression_n  
SUM(aggregate_expression)  
FROM tables  
[WHERE conditions]  
GROUP BY expression1, expression2, ... expression_n;

示例1：

假设有一个名为student的表，具有以下数据：

从student表中检索AGE小于24的学生总费用：

SELECT SUM(FEES) AS "Total Fees"  
FROM STUDENT  
WHERE AGE < 24;

执行上面查询代码，得到以下结果 -

sqlite> SELECT SUM(FEES) AS "Total Fees"
   ...> FROM STUDENT
   ...> WHERE AGE < 24;
34000.0
sqlite>

示例2：

使用具有数学公式的SUM()函数，求每个月的学生总费用 -

SELECT SUM(FEES / 12) AS "Total Monthly Fees"  
FROM STUDENT;

执行上面代码，得到以下结果 -

sqlite> SELECT SUM(FEES / 12) AS "Total Monthly Fees"
   ...> FROM STUDENT;
14083.3333333333
sqlite>

示例3：

计算每个地址的学生总人数，按学生地址(Address)分组。

从student表中检索地址，并按地址分组并查找相应费用的总和。

SELECT ADDRESS, SUM(FEES) AS "Total Salary"  
FROM STUDENT  
WHERE ID > 0
GROUP BY ADDRESS;

执行上面代码，得到以下结果 -

sqlite> SELECT ADDRESS, SUM(FEES) AS "Total Salary"
   ...> FROM STUDENT
   ...> WHERE ID > 0
   ...> GROUP BY ADDRESS;
Beijing|15000.0
Guangzhou|70000.0
Haikou|35000.0
Shanghai|2000.0
Shengzhen|38000.0
Shenzhen|9000.0
sqlite>