加入MySQL的连接两个表MAX（值）

Question

my question is how to get max share by news id where created_at is today? 

尝试 SELECT MAX（shares.id），脸谱从股份GROUP BY shares.id ORDER BY Facebook的DESC LIMIT 20;

select * from shares; 

+-------+----------+ 
| id | facebook | 
+-------+----------+ 
| 1  |  584 | 
| 1  |  610 | 
| 2  |  354 | 
| 2  |  360 | 
| 2  |  467 | 
| 1  |  1324 | 
| 2  |  924 | 
+-------+----------+ 

select * from news; 

+----+-------------------------------+------------+ 
| id | url_address     | created_at | 
+----+-------------------------------+------------+ 
| 1 | http://www.google.com   | 1417496667 | 
| 2 | http://www.facebook.com  | 1417491832 | 
+----+-------------------------------+------------+ 

Answer 1

试试这个：

SELECT s.id, SUM(s.facebook) 
FROM shares s 
INNER JOIN news n ON s.id = n.id 
WHERE n.created_at = UNIX_TIMESTAMP(CURRENT_DATE()) 
GROUP BY s.id 
ORDER BY SUM(s.facebook) DESC 
LIMIT 20;