Quetions on Joins

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От Alex
Тема Quetions on Joins
Дата
Msg-id 3F5228D6.7020009@meerkatsoft.com
обсуждение исходный текст
Ответ на Re: Question Join/Subselect  ("Andrew L. Gould" <algould@datawok.com>)
Ответы Re: Quetions on Joins  (Stephan Szabo <sszabo@megazone.bigpanda.com>)
Re: Quetions on Joins  (Ron Johnson <ron.l.johnson@cox.net>)
Список pgsql-general
Hi,

I have a query where I want to filter out records from table_a if a
field in table_a matches in table table_b. Basically table_b defines the
filter.

If table_b however is empty i dont get any results

SELECT A.value_one FROM table_a AS A, table_b AS B WHERE  A.value_two <>
B.value_two;
or
SELECT A.value_one FROM table_a AS A, table_b AS B WHERE  A.value_two <>
B.value_two AND B.value_two NOTNULL;

Only work if the there is a value in table_b.
Could anyone tell me if there is a way to do that ?


Thanks a lot
Alex

PS: I'd like to thank here persons who reply rather than sending the
message per mail.




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