Question

Table 1

person_id| location_id | field a | field b |friend_id

Table 2

location_id | location_name

friend_id is the id of a person liked by the given person ( it’s an optional field and the default value is zero )

How can I query the two tables to get the following :

the location_name of the person who has been liked by the maximum people and so on in decreasing order.

Answer 1

First, ensure you have an index on the Friend_ID column so it can be optimized in the query

select
      P.Person_ID,
      P.FieldA,
      P.FieldB,
      L.Location_Name,
      ByPopularity.Popular
   from
      ( select T1.friend_id, count(*) as Popular
           from Table1 T1
           group by T1.friend_id
           order by Popular DESC ) ByPopularity

         JOIN Table1 P
            on ByPopularity.Friend_ID = P.person_ID

            Join Table2 L
               on P.Location_ID = L.Location_ID

EDIT — PER COMMENT on how to get most popular location based on people originations

select
      L.Location_Name,
      ByPopularity.PopularLocation
   from
      ( select T1.Location_ID, count(*) as PopularLocation
           from Table1 T1
           group by T1.Location_ID
           order by PopularLocation DESC ) ByPopularity

           Join Table2 L
               on ByPopularity.Location_ID = L.Location_ID