Обсуждение: Left joins

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Left joins

От
Peter Eisentraut
Дата:
Does anyone know an elegant way of doing a left join like

Table 1
abc    1
def    2
ghi    <NULL>

Table 2
1    foo
2    bar
3    duh

I'd like to join those to give me:
abc    1    foo
def    2    bar
ghi    <NULL>    <NULL>

I can currently only envision a way to do this via a union of several
queries filtering out null and non-null fields, but that gets very
cumbersome when you have lots of fields involved and more than two or
three tables to join.

Any suggestions?

Thanks.

-- 
Peter Eisentraut
PathWay Computing, Inc.