Question

I have a table members:

member_id, points

And I have another table bets:

member_id, finished

Consider following data for table members:

1 0
2 15000
3 0

And for bets:

1 -1
1  0
2  1
3  1
3 -1

In the table bets finished = -1 marks the bet as lost, 0 as unfinished and 1 as won.
How can I select member id’s which have 0 points and all their bets are finished? With the data I have given, it should return one row with member id = 3.

Answer 1

You could use EXISTS clause:

select members.id
from members
where
  points=0
  and not exists (select null from bets where bets.id=members.id and status=0)

You can also use a LEFT JOIN:

select members.id
from
  members left join bets
  on members.id = bets.id
     and bets.status=0
where
  bets.id is null
  and members.points=0