MySQL most relevant weighted search results based (MATCH AGAINST).
select *, (
(1.2 * (MATCH(title) AGAINST (`".$keyword."` in BOOLEAN mode))) +
(0.8 * (MATCH(description) AGAINST (`+".$keyword."` in BOOLEAN mode))) +
(1.0 * (MATCH(tags) AGAINST (`".$keyword."` in BOOLEAN mode)))
) as relevance
from `".$table_posts."`
where match (title, description, tags) AGAINST ('".$keyword."' in BOOLEAN mode)
order by relevance desc
limit 0, 5;