将这两条SQL语句组合为一条的最佳方法是什么?我试着使用union,但似乎毫无进展。
select id as id from likes where type=1;
select sum(votes) as votes from likes where parent=id;
以下是likes
表格:
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
这就是我试图实现的结果:
id | votes
---------------
1 | 9
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;
点击此处查看实际操作:
- SQL Fiddle演示
这将给你:
| ID | TOTALVOTES |
-------------------
| 1 | 9 |
SELECT SUM(votes) AS votes
FROM likes
WHERE parent IN (SELECT id FROM likes WHERE type=1)
HTH
我相信这应该能解决你的问题:
SELECT parent AS id, SUM(votes) AS votes FROM likes WHERE parent IN (SELECT id FROM likes WHERE type = 1) GROUP BY parent;
你可以试试这个
select id,sum(votes) as votes from likes where type=1 and parent=id;
希望这能帮助