SQL查询来计数标记的帖子

Question

I have a table of newsPosts where i have a column tags in that table. tags column contains comma(,) seperated tags like this.

tag1,tag2,tag3

in another table i have list of all tags under tag column like this :

tag

tag1
tag2
tag3
tag4
.
.
.
. 

I want to find number of posts from news post table which are tagged with say tag2.

how can i do this ? i am using mysql 5.0

EDIT ::

what i want to do is ::: find tags which are used highest number of times to tag a newsPost.

like this :

    tag1 x 100 times
    tag2 x 1000times
                 .
                 .
    tagN x 500 times 

tag2 should come on the top of the result.

Answer 1

Just say

SELECT * FROM newsPosts WHERE tags LIKE '%tag2%'

Demo at sqlfiddle

Answer 2

这应该工作：

SELECT * FROM newPosts WHERE tags LIKE "%tag2%"; 

Answer 3

It should work for all tags from tags table :

SELECT tag, (SELECT COUNT(1) 
             FROM tag_newPosts t2
             WHERE t2.tag LIKE CONCAT('%',t1.tag,'%')) AS tag_count
FROM tags t1;

Answer 4

You can query with regular expressions:

select *
from newsPosts
where tags regexp '(^|,)tag2(,|$)'

This expression prevents tags contained inside other tags from making it into the query results. For example, it would select items with tag2 , but not with mytag22 .