如何汇总不同的值？

Question

+---+------------+
|sid| discounts  | 
+---+------------+
| 1 | 10.00      |
| 2 | 20.00      |
  2 | 20.00      |
+---+------------+

我需要获得列折扣的总和，但是如果列sid具有相同的值，则只添加一行而不是全部。

所以我需要说30.00而不是50.00

我试过这样的事情

 SELECT DISTINCT sid FROM (SELECT SUM(discounts) FROM $table_name)

和

SELECT SUM(discounts) FROM $table_name WHERE sid IN (SELECT DISTINCT 'sid' FROM $table_name)

我刚刚收到您的SQL语法错误＆＃39;

Answer 1

如果您删除single quuto betwwen sid

，则第二个查询将有效

SELECT SUM(discounts) FROM $table_name WHERE sid IN (SELECT DISTINCT sid FROM $table_name)

Answer 2

select sum(discounts) from (select discounts,sid  from $table_name group by sid) t

Answer 3

我希望这会起作用

$sql=mysql_query("select SUM(discounts) from table_name groub by sid");

Answer 4

它很简单，你可以使用

select SUM(discount) from (SELECT discount FROM  `table_name` group by sid) as discount

希望这对您有用

Answer 5

您可以尝试以下SQL：

select 
    sum(t.discount) 
from 
    (select 
        distinct sid, discount 
    from 
        $table_name
    ) t

DEMO