Sådan sletter du dubletter i SQL-tabel baseret på flere felter

Du bør være i stand til at lave en korreleret underforespørgsel for at slette dataene. Find alle rækker, der er dubletter, og slet alle undtagen den med det mindste id. For MYSQL skal en indre joinforbindelse (funktionel ækvivalent til EXISTS) bruges, som sådan:

delete games from games inner join 
    (select  min(id) minid, date, time,
             hometeam_id, awayteam_id, locationcity, locationstate
     from games 
     group by date, time, hometeam_id, 
              awayteam_id, locationcity, locationstate
     having count(1) > 1) as duplicates
   on (duplicates.date = games.date
   and duplicates.time = games.time
   and duplicates.hometeam_id = games.hometeam_id
   and duplicates.awayteam_id = games.awayteam_id
   and duplicates.locationcity = games.locationcity
   and duplicates.locationstate = games.locationstate
   and duplicates.minid <> games.id)

For at teste skal du erstatte delete games from games med select * from games . Kør ikke bare en sletning på din DB :-)