Mysql从另一个表中选择sum（）

I have this tables :

Table: Articles

   id   |   title   |   display   |
 -----------------------------------
    1   |   Fkekc   |      1      |
    2   |   ldsdf   |      1      |
    3   |   OTRld   |      0      |
    4   |   QCRSA   |      1      |

Table: Likes

   id  |  article_id |   like   |  type
 ----------------------------------------
    1   |      1     |   121    |   1
    2   |      1     |   652    |   2
    3   |      2     |   12     |   1
    4   |      1     |   5      |   3

i want get this result:

Article [1] => 778
Article [2] => 12
Article [3] => 0
Article [4] => 0

I use LEFT JOIN between two tables but this return records per likes table. so i get three record of article 1

My code:

 SELECT articles.*,likes.like FROM `articles` LEFT JOIN `likes` ON articles.id=likes.article_id WHERE display='1'

I know that i must use SUM() but i didn't know how use it

With your answers i find that i must use this:

SELECT articles.*, sum(likes.like) as likesSum FROM `articles` LEFT JOIN `likes`ON articles.id=likes.article_id WHERE display='1' GROUP BY articles.id

But i want to set filter in query. so use this :

SELECT articles.*, sum(likes.like) as likesSum FROM `articles` LEFT JOIN `likes`ON articles.id=likes.article_id WHERE display='1' && likesSum>='100' GROUP BY articles.id

But above code doesn't return any result

This is your query

SELECT articles.*,COALESCE(sum(likes.like),0) as total_like  FROM 
`articles` LEFT JOIN `likes` ON articles.id=likes.article_id group by   
articles.id

Output is

  SELECT articles.*, sum(likes.like) as likesSum FROM `articles` LEFT JOIN `likes`ON articles.id=likes.article_id WHERE display='1' GROUP BY articles.id

You did everything right but only one this missing. You should have used group by

SELECT articles.*, likes.like 
FROM `articles` 
LEFT JOIN `likes` ON articles.id = likes.article_id 
WHERE display = '1' 
GROUP BY likes.article_id

This visual representation is great to understand the joins: http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

This should work for you perfectly..

SELECT articles.id, sum(likes.like) from articles left join likes on (articles.id=likes.article_id) group by articles.id order by articles.id

See the use of SUM() with GROUP BY