查询次数，金额，与条件在一个查询与MySQL

Question

我有这个表在MySQL数据库：

TABLE rating 
| id   (int, primary) 
| id_company (int, index) 
| state  (enum: 'waiting','done','refuse') 
| rating  (int between 1 and 5) 

我想这个统计为一个id_company：

• 号线
• 行数与状态=做
• 总和等级
• 总和评级，状态=做
个

为此，我有2个查询（用为例= id_company 2）：

SELECT COUNT(1) as `nbr`, SUM(`rating`) as `total` FROM `rating` WHERE `id_company`=2 
SELECT COUNT(1) as `nbr`, SUM(`rating`) as `total` FROM `rating` WHERE `id_company`=2 AND `state`='done' 

但它有可能使一个独特的查询得到这个统计？

Answer 1

你可以尝试这样的事情：

SELECT COUNT(*) as `nbr1`, 
     SUM(`rating`) as `total1`, 
     SUM(`state`='done') as `nbr2`, 
     SUM(CASE 
       WHEN `state`='done' THEN `rating` 
       ELSE 0 
      END) as `total2` 
FROM `rating` 
WHERE `id_company`=2