Select DISTINCT with multiple OR in sql query

Question

I am trying to write a query with multiple OR and using DISTINICT for multiple column.But the result is NULL what i am missing in my query. Anyone can help me here please.

SELECT DISTINCT 
   P.user_p_id, 
   P.surl, 
   M.user_id, 
   M.user_p_id 
   FROM users P, page M 
   WHERE (P.user_p_id = '$urlid' OR P.surl = '$urlid' OR M.user_id = '$urlid' OR M.user_p_id = '$urlid')

Answer 1

You should do a proper join with an ON clause:

SELECT DISTINCT 
   P.user_p_id, 
   P.surl, 
   M.user_id, 
   M.user_p_id 
   FROM users P INNER JOIN page M 
   ON M.user_id = P.user_p_id
   WHERE '$urlid' IN (P.user_p_id, P.surl, M.user_id, M.user_p_id)

I use ON M.user_id = P.user_p_id although it's not clear if you want these columns to be matched.
You may change the type of the JOIN to LEFT if this is what you need.