将这两个SQL语句合并为一个

Question

将这两个SQL语句合并为一个的最佳方式是什么？我尝试过使用联盟，但似乎无处可去。

select id as id from likes where type=1; 

select sum(votes) as votes from likes where parent=id; 

这里是likes表：

id type parent country votes 
1  1  0  US  0 
2  2  1  US  6 // This + 
19  3  1  US  3 // This 
3  3  2  US  3 
7  3  2  US  3 
4 10  3  US  1 
5 10  3  US  1 
6 10  3  US  1 
10 10  7  US  1 
9 10  7  US  1 
8 10  7  US  1 
20 10  19  US  1 
21 10  19  US  1 
22 10  19  US  1 

这是我想要达到的效果：

id | votes 
--------------- 
1 | 9 

Answer 1

试试这个：

SELECT 
    l1.id, 
    SUM(l2.votes) AS Totalvotes 
FROM likes AS l1 
INNER JOIN likes AS l2 ON l1.id = l2.parent 
WHERE l1.type = 1 
GROUP BY l1.id; 

看到它在此采取行动：

• SQL Fiddle Demo

这会给你：

| ID | TOTALVOTES | 
------------------- 
| 1 |   9 | 

Answer 2

SELECT SUM(votes) AS votes 
FROM likes 
WHERE parent IN (SELECT id FROM likes WHERE type=1) 

HTH

Answer 3

你可以试试这个

select id,sum(votes) as votes from likes where type=1 and parent=id; 

希望这有助于

Answer 4

这应该解决您的问题，我相信：

SELECT parent AS id, SUM(votes) AS votes FROM likes WHERE parent IN (SELECT id FROM likes WHERE type = 1) GROUP BY parent;