Another way to improve the SQL Query to avoid union?

Question

User can search by Postcode (eg: L14, L15, L16) or Location from a textbox.

If user type in \"Liverpool\", it will find all the shops that are located in \"Liverpool

Answer 1

please try this:

SELECT DISTINCT shops.*, 
       DA.delivery_cost, 
       DA.postcode 
FROM shops 
       JOIN shops_delivery_area as DA on DA.shop_id = shops.id
WHERE DA.postcode = "Liverpool" 
      OR (location = "Liverpool" and DA.postcode = shops.postcode)