SQL query with AND OR operator

I have this sql query

SELECT entries.*, categories.name as name_cat, areas.name as name_area, sub_categories.name as name_sub
FROM entries, areas, sub_categories, categories
WHERE sub_categories.id= entries.id_sub
  AND **areas.id = entries.area**
  AND categories.id = entries.id_cat
ORDER BY entries.id DESC

It works good but i do have some BLANK fields in entries.area .. which is not coming in result..

I try few changes in query but some give me result while some give less nothing gives me proper Answer