Hi SJH, thanks for your reply.
I tested my search again.
I found that if I search for keyword "rack" with $q2, it return 0 result. When I search keyword "racks" with $q2 again, it will return 2 results.
It seems full text search will not match the keyword in the %like% way.
Is there any solution I can do cause my search causing my site down so I thinking to convert all the search using %like% method to full text search.
I tried adding "WITH QUERY EXPANSION" in the query, but the result is zero.
SELECT * FROM ".T_CATEGORIES."
WHERE MATCH (
WITH QUERY EXPANSION