php - 将这两条 SQL 语句合二为一

Question

将这两个 SQL 语句合并为一个的最佳方法是什么？我尝试使用 union，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

这是我想要达到的结果:

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;

在此处查看实际效果:

• SQL Fiddle Demo

这会给你:

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