The following was ran from the immediate window of Access 2007:

?DLookup("PurgePeriod", "Info") = ""
True

?IsNumeric("")
False

?IsNumeric(DLookup("PurgePeriod", "CompanyInfoMaster"))
True


Huh? Is someone able to explain this?

Vincent

Vincent wrote:

The value of a boolean (yes/no) field is either -1 (representing true)
or 0 (false).
Try using IsNumeric in a query and you see only -1 or 0 in the column.

--
Groeten,

Peter
http://access.xps350.com


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Vincent wrote:
random row in the domain (table) you are searching ...

Given that, perhaps the PurgePeriod field in the Info table contains an
empty string in the random row examined by DLookup, and the PurgePeriod in
CompanyInfoMaster contains a number in the random row selected by Dlookup?

--
Bob Barrows

On Jun 8, 10:42*am, "Bob Barrows" <reb01... (AT) yahoo (DOT) com> wrote:
Nope. There is only one row in this table.

Vincent

Vincent wrote:
told us what DLookup returns from Info. What does it return from
CompanyInfoMaster?

--
Bob Barrows

On Jun 8, 10:06*am, XPS35 <xps... (AT) gmail (DOT) com> wrote:
The "PurgePeriod" field is an integer field. If I try using IsNumeric
in a query, I see a value of 0 in the column, which would indicate
false. But, why is the above scenario showing a value of true?

On Jun 8, 10:59*am, "Bob Barrows" <reb01... (AT) yahoo (DOT) com> wrote:
I'm sorry. I was trying to abbreviate and only abbreviated one spot.
They are both looking at the same table.

Vincent

Vincent wrote:
I have an existing table called Junk. It has some records in it. I
added a field called Junk1, type number longint. I run a query and it I
enter Expr1: IsNumeric([junk1]). It returns 0. If open the table,
Junk1 is blank. When I run an update query to set Junk1 to 0, it of
couse returns -1 when I check the numeric status.

I created a new table Table1. I created 2 fields Junk and Junk1. I
left the default as 0 in Junk and removed the default in Junk1. I
entered 123 in Junk. Then checked Isnumeric on both fields. Junk was
-1, Junk1 was 0.

Salad wrote:
That's because Junk1 contains Null and IsNumeric(null) returns false.
--
Bob Barrows

Vincent wrote:
First of all, a Number field can never contain an empty string. Strings
(Text - empty or otherwise) and Numbers are mutually exclusive. So, given
that PurgePeriod is indeed a Number field with a Long or Short "Field Size"
setting, your first test (?DLookup("PurgePeriod", "Info") = "") should
always return false.

Now,you say the test returned True. I cannot duplicate this result, even
with a Text field - if there is no value in the field (Null), or the field
contains an empty string, that test never returns true, whether it's a Text
or a Number field). The test returns true in a query,
Select [textfield]="" AS EmptyString? From Test WHERE Field1=1

but my attempts with Dlookup have never returned True. If it is a Text field
containing an empty string (as confirmed in a query) Dlookup always returns
Null for some reason.

So I guess it's time for the guessing to stop. What is the actual datatype
of the field in question? Text or Number? What is the Required property set
to? If it is a Text field, is Allow Zero String set to true? If it is
Required, does it have a default value set? And lastly, what is the value
contained in the field?

If it is a Number field, why on earth are you bothering with IsNumeric()?
Either the field contains a value which has to be numeric, or it contains
Null. There is no third choice which would allow it to contain non-numeric
value. If you are concerned as to whether it contains a value, just use
IsNull() to check the value returned. Or use Nz as the expression in your
call to DLookup:

PurgePeriod=Dlookup("Nz([PurgePeriod],0)","CompanyInfoMaster")


PS. There is a documented behavior of Isnumeric that some people think is a
bug: some alpha characters are considered to be numeric by IsNumeric: "e"
and "d" are used for entering exponents (scientific notation) in Single and
Double fields so IsNumeric will return true for a string containing those
characters.

Actually, I'm through guessing.

--
Bob Barrows