SQLite SUM()函數

SQLite SUM()函數用於返回表達式或給定數字列的總和。

語法

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

在SUM()函數中使用GROUP BY子句時的語法：

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

示例1：

假設有一個名爲student的表，具有以下數據：

從student表中檢索AGE小於24的學生總費用：

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

執行上面查詢代碼，得到以下結果 -

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

示例2：

使用具有數學公式的SUM()函數，求每個月的學生總費用 -

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

執行上面代碼，得到以下結果 -

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

示例3：

計算每個地址的學生總人數，按學生地址(Address)分組。

從student表中檢索地址，並按地址分組並查找相應費用的總和。

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

執行上面代碼，得到以下結果 -

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>