Find related post in mysql

[vinoth1986]

Hi All,
I have data table which contains fields "id, title, post_data,tag(comma separated)" and tag_name table which contains id,tag.

Now I need to find most relevant topic for a particular post by using the tag, Which is having more similar tags.

[oddz]

Why are the posts tags in a comma separated list as opposed to a separate table that relates a tag to a post?

[vinoth1986]

Because I want to display cloud tag like in wordpress... For that I need the tag name and number of post mentioning the tag.

[guido2004]

Normalize your database by eliminating the column with comma separated values, and create a new table (posttags) instead (like oddz says). That new table will contain a row for each post-tag couple.