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source: Mysql Manual - 13.2.10.2 JOIN Clause Your query would be interpreted as if it were: select * from trk_races a inner join drivers d left outer join ( select race_winner, count(race_date) as wins from trk_races where race_winner > '' and Season='$selyr' group by race_winner ) w on w.race_winner = a.race_winner on 1=1 Essentially your left join becomes like a sub-join of the drivers table. When you do a join like that you can only reference the parent join table (d) or some same-level sibling table (none here) in your on clauses. Table a does not meet either of those conditions (it's a sibling of the parent) so it's invalid in your left join's ON clause. In case it's unclear, when I say sibling tables I mean something like this. select * from a left join b inner join c on c.Id=b.cID inner join d on d.Id=c.dID on a.Id=b.aID Table c is a sibling to table d, so it can be used in the on condition, as can table b as it's the parent table. Table a cannot because it's the parent's sibling.