来自mySQL结果的汇总总数

Question

在codeiginter中 - 是否可以使用Active记录来汇总mySQL中的结果？

我的表：

+-----------------+---------------+----------+ 
| transaction_ID | category_ID | amount | 
+-----------------+---------------+----------+ 
|  1  |  2  | 5.0 | 
+-----------------+---------------+----------+ 
|  2  |  1  | 6.0 | 
+-----------------+---------------+----------+ 
|  3  |  2  | 4.1 | 
+-----------------+---------------+----------+ 
|  4  |  3  | 1.2 | 
+-----------------+---------------+----------+ 
|  5  |  1  | 7.0 | 
+-----------------+---------------+----------+ 

我想什么来实现：

+---------------+----------------+ 
| category_ID | total_amount | 
+---------------+----------------+ 
|  1  |  13.0  | 
+---------------+----------------+ 
|  2  |  9.1  | 
+---------------+----------------+ 
|  3  |  1.2  | 
+---------------+----------------+ 

Answer 1

试试这个，

SELECT category_ID, SUM(amount) totalAmount 
FROM tableName 
GROUP BY categoryID