CareerCup

create table user(
userid int, 
username varchar(200) 
)

create table race(
raceid int, 
racename varchar(200)
)


create table user_race(
userid int, 
raceid int, 
iscompleted varchar(2)
)
/*1*/
select * from user; 

/*2*/
select r.* from race r where exists 
(select 1 from user_race ur where ur.raceid = r.raceid and ur.userid = '::USERID::'); 

/*3*/
select r.* from race r where
exists 
(select 1 from user_race ur 
 where ur.raceid = r.raceid 
   and ur.iscompleted = '1'
   and ur.userid = '::USERID::')


/*4*/
select r.* from race r where
exists 
(select 1 from user_race ur 
  where ur.raceid = r.raceid 
    and ur.iscompleted = '0'
    and ur.userid = ':::USERID:')

/*5*/
select r.raceid
from user u, user_race ur, race r
where 
u.userid = ur.userid and ur.raceid = r.raceid
group by r.raceid
having COUNT(ur.userid) = 2