Question

Somehow am not successful with creating the query that I want.

DB is to do with locations, there are the following tables which are relevant

• t_location – list of locations incl. field t_location_zipcode, and t_location_id_location
• t_zipcodecity – join table just t_zipcodecity_zipcode t_zipcodecity_id_city
• t_city – city list with t_city_id_city
• t_citystate – join table, t_citystate_id_city, t_citystate_id_state
• t_state – list of states with t_state_id_state

Initially I tried to get a list of states with locations using this query:

SELECT DISTINCT `t_state_id_state`
      , `t_state_name_full` 
  FROM (`t_state`) 
LEFT JOIN `t_citystate` ON `t_state_id_state` = `t_citystate_id_state` 
LEFT JOIN `t_city` ON `t_citystate_id_state` = `t_city_id_city` 
LEFT JOIN `t_zipcodecity` ON `t_city_id_city` = `t_zipcodecity_id_city` 
LEFT JOIN `t_location` ON `t_zipcodecity_zipcode` = `t_location_zipcode` 
ORDER BY `t_state_name_full` asc ­

which works fine.

Now what I also need / want which I am failing dismally at is to get the number of locations in each state. I don’t know if it can be done in this one query or if i need another, either way I need help!

Answer 1

SELECT  t_state_id_state
      , t_state_name_full 
      , COUNT(DISTINCT t_location_id_location) AS locations_number

  FROM 
        t_state
    LEFT JOIN 
        t_citystate   ON t_state_id_state = t_citystate_id_state 
    LEFT JOIN 
        t_city   ON t_citystate_id_state = t_city_id_city 
    LEFT JOIN 
        t_zipcodecity   ON t_city_id_city = t_zipcodecity_id_city 
    LEFT JOIN 
        t_location   ON t_zipcodecity_zipcode = t_location_zipcode 

  GROUP BY t_state_id_state 

  ORDER BY t_state_name_full ASC ­