leolas95

delimiter //
create procedure hacer_intercambio(in groupid int, out a varchar(200), out b varchar(200))
begin
  drop table if exists temp1;
  drop table if exists temp2;
  -- Crea una tabla temporal para guardar los ids de los participantes
  create temporary table temp1 as (select users.id from
    users, participants, participates
    where participates.participant_id = participants.id and
          participants.user_id = users.id and