where to find union query sql

S

S.Hoitinga

Hi

Can anyone please explain to me what the function (besides compact overview)
of a union-query could be.
Can onyone pelase tell me where to find instructions on how to write sql for
the union query.

thank you.

Sybolt
 
S

Steve Huff

What the function is - as in an example? Well let's say you have a table
with suppliers addresses and a table with customer addresses and you want a
report to list all of them, for the purpose of sending them Christmas cards
:). You could UNION the two tables together and report on them as one big
happy family like this:

SELECT [CompanyName], [City]
FROM [Suppliers]

UNION SELECT [CompanyName], [City]
FROM [Customers]
ORDER BY [City];


If you search for UNION in Access Help you will find plenty of information
on it's syntax.
 
S

S.Hoitinga

Thanks Steve,

In the Northwind database that ships with Access there is a union query.
In the SQL there is a syntax that uses select fields as relation. I didn't
understand that one.
Your example is quite a lot simpler.
The general idea is that fields in different tables have exactly the same
name, I suppose.

Any idea why there is no graphical interface to create unionquery's?

greets

Sybolt
 
J

John Vinson

The general idea is that fields in different tables have exactly the same
name, I suppose.
Click to expand...

The field *names* can be the same or different, it makes no
difference. However you must have the same number of total fields, and
they must match in datatype and size: that is if you select a Long
Integer Number, a Text, and a Date in one of the SELECT clauses of the
UNION, you must select a Long Integer Number, a Text, and a Date in
each of the SELECTs.
Any idea why there is no graphical interface to create unionquery's?
Click to expand...

They're an uncommonly used and rather advanced technique. The query
grid is simply a user friendly tool to create SQL strings; the SQL is
"the real query". Since a UNION query can be quite complex (you could
have a dozen tables with different fieldnames and criteria) and since
most uses of a UNION presuppose that you're intentionally using an
advanced tool, the GUI interface would be more trouble to build and
use than it would be worth - or so I read Microsoft's attitude.

John W. Vinson[MVP]
 
S

S.Hoitinga

John,

Thanks a lot.
I now know how to create them.
I also added a new field (using as) to let you know for instance the table a
record comes from.

For my purposes I know enough at the moment.

Greets,

Sybolt
 
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