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Selecting from a union join?

Author

Topic

kleinmi
Starting Member

9 Posts

Posted - 2002-07-10 : 11:00:59

How can I select from a union join?

ex.

select *
from
(
(select * from table1) union all (select * from table2)
)

This doesn't work, but this is the basic logic behind what i'm trying to do

Thanks for any help!
Michael

MakeYourDaddyProud

184 Posts

Posted - 2002-07-10 : 11:05:06

quote:

select *
from
(
(select * from table1) union all (select * from table2)
)

... you are missing a correlation name off the SQL

Try...

select *
from
(
select * from table1
union all
select * from table2
) as Table1_2

Remember that the number of columns and datatype for table1 and table2 must match exactly

Daniel Small MIAP
www.danielsmall.com IT Factoring

robvolk
Most Valuable Yak

15732 Posts

Posted - 2002-07-10 : 11:06:19

Why not:

select * from table1
union all
select * from table2

You don't need to make a subquery out of it.

FYI, if you do use a subquery, you need to alias it with a name:

select * from (select * from table1 union all select * from table2) AS subQuery

Edited by - robvolk on 07/10/2002 11:07:01

MakeYourDaddyProud

184 Posts

Posted - 2002-07-11 : 03:40:51

Making a subquery of it might be required if the developer wanted to join to the consildated SELECTs as a whole, although performance and table scanning might be an issue.

Daniel Small MIAP
www.danielsmall.com IT Factoring

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