Criteria to return all records if selection from form is null


S

Sue Pari

Hi,

I'm trying to pass multiple query criteria from form controls. I'm using
the following type of syntax for the criteria:

Like Nz([Forms]![ViewEdit Completed Procedures]![SelectOBy],"*")

And this works fine for the fields where there are no Nulls in the data, but
if there are Nulls in this field I don't get those records. Quite
understandable since Like "*" doesn't return Nulls.

What I'm trying to do is to return all records when there is nothing chosen
in the selection box on the form. I've tried a bunch of different IIfs with
various use of quote marks, on the order of:

IIf(IsNull([Forms]![ViewEdit Completed Procedures]![SelectOBy]),"Not Is Null
Or Is Null",[Forms]![ViewEdit Completed Procedures]![SelectOBy])

but they either don't get all the records or they kick a "too complex"
error.

I'm sure this must be easier than I'm making it. Could anyone give me some
help?

Thanks in advance,

Sue
 
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A

Allen Browne

It is possible to craft the WHERE clause of the query to it evaluates to
TRUE if the control on the form is null.

Switch the query to SQL View.
Locate the WHERE clause. It will be something like this:
WHERE SomeField = [Forms]![ViewEdit Completed Procedures]![SelectOBy]
Change it like this:
WHERE (([Forms]![ViewEdit Completed Procedures]![SelectOBy] Is Null)
OR ([SomeField] Like [Forms]![ViewEdit Completed
Procedures]![SelectOBy]))

Be careful with the bracketing when mixing ANDs and ORs.

This approach quickly gets unwieldy as you add more options.
It is much more efficient to build a filter string dynamically.
This article explains how to do that:
Search form - Handle many optional criteria
at:
http://allenbrowne.com/ser-62.html
Includes a downloadable sample file (free.)
 
J

John Spencer

Sue,

One additional possibility if your table is fairly small OR if the field is
not indexed. Add a zero-length string to the field. You can do this even if
the field is indexed, it just means that the index won't be used and the query
will take a bit longer to run.

Field: MySearchField: [Name of Field] & ""
Criteria: Like Nz([Forms]![ViewEdit Completed Procedures]![SelectOBy],"*")

You can experiment with this and see if the performance hit is acceptable.

John Spencer
Access MVP 2002-2005, 2007-2010
The Hilltop Institute
University of Maryland Baltimore County
 
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S

Sue Pari

Thanks to you all for the excellent advice! I'll work through the different
approaches and see what I can do. I really appreciate the help.

Sue
 

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