Reputation: 2256
Currently I am doing this query:
select a.x, b.x, c.x
from number as a, customer as b, numbergroup as c
where a.b = b.b and a.c = c.c and c.b = b.b
However, I want to retrieve records from table "a" even if "a.c = null", which is not retrieved due to the join between "a" and "c".
I have found information about left join
but I don't know how to do it when the query involves more than two tables like in this case.
Upvotes: 20
Views: 75091
Reputation: 9252
select a.x, b.x, c.x
from number as a
left join customer as b on a.b = b.b
left join numbergroup as c on a.c = c.c and c.b = b.b
Upvotes: 45