MySQL左連接2個表按次數排序

Question

我有2個表格，如下所示，並且希望通過計數（列）選擇它們兩者，但不工作請指教。

review table 

ID | RID | Name | comment 
555|3000 | John | John comment 
555|3001 | Ben | Ben comment 
555|3002 | Smith| Smith comment 

Likes table 

U | PID 
1 | 3000 
2 | 3000 
3 | 3000 
4 | 3001 


Expected result 

ID | RID | Name | comment  | votes 
555|3000 | John | John comment | 3 
555|3001 | Ben | Ben comment | 1 

我從選擇從喜歡錶期待的結果*從審查，計數PID列

我當前的查詢是

SELECT * , (SELECT COUNT(PID) FROM Likes AS votes WHERE there.ID = PID) 
FROM review AS there 
LEFT JOIN Likes b ON there.RID = b.PID 
WHERE ID =555 
AND there.RID = b.PID AND votes>0 
ORDER BY votes DESC 

但是，這並不沃金，請告知。

Answer 1

由於您使用的審查，只有票後，就可以通過轉換LEFT JOIN至INNER JOIN，並消除COUNT檢測讓您的查詢較短（也許更快）：http://www.sqlfiddle.com/#!2/1f920/3

SELECT r.ID, r.RID, r.Name, `Comment`, COUNT(RID) as votes 
FROM review r 
JOIN Likes l ON l.PID = r.RID 
WHERE r.ID = 555 
GROUP BY r.RID 
ORDER BY votes DESC 

輸出：

| ID | RID | NAME |  COMMENT | VOTES | 
-------------------------------------------- 
| 555 | 3000 | John | John comment |  3 | 
| 555 | 3001 | Ben | Ben comment |  1 | 

Answer 2

SELECT ID, RID, Name, `Comment`, COUNT(RID) as votes 
FROM review AS there 
LEFT JOIN Likes b ON there.RID = b.PID 
WHERE ID = 555 
AND there.RID = b.PID 
GROUP BY b.PID 
HAVING votes > 0 
ORDER BY votes DESC 

sqlfiddle