Maximum Unions in Access 2000

D

David Gartrell

Hi,

Does anyone know please what the maximum number of unions is in an Access
2000 query?

I may need to produce a union query with 85 unions in and i'm trying to find
out if this is possible or not. Each union would contain 6 lines of code.

Many thanks

David.
 
J

John Spencer

85 is probably too many.

There is no simple answer to the maximum number of unions. It depends on
several factors:
The max number of fields in a query is 255 - so if each of the unioned queries
has 3 fields (no more) then you might squeak in under this limit.

The total size of the query when compiled has a limit.

The complexity of the query may be too great.

You might have to resort to using the queries to populate a work table.


John Spencer
Access MVP 2002-2005, 2007-2008
The Hilltop Institute
University of Maryland Baltimore County
 
D

David Gartrell

Thanks for your help John. That's exactly what I was looking for.

Each of my unions would have 11 fields so obviously this would make it
completely unworkable?
 
M

Michel Walsh

This is a limit of 32 tables per query (under Help, search Specifications),
so I imagine you can only use 31 times, maximum, the clause UNION (all).
(Untested, I don't know if using the same table twice counts for 2 tables,
or still only one).

Vanderghast, Access MVP
 
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