SQL: Comparing Two Double Fields, Getting False Diffs?

[(PeteCresswell)]

I'm equi-joining two tables on a Long and a DateTime field and then
comparing an amount in one with an amount the other via an Immediate If
statement.

Problem is that for some (not all...not even most...) records, I am getting
false differences.

I know the stuff below probably looks like a rat's breakfast, but I'm at the end
of my little string on this. Similar things are happening in a couple other
queries, so I'd have to assume it's something dumb that I'm doing...but I can't
figure out what.

If anybody's got time on their hands and/or some excess curiosity, I could email
you the sample DB - it's only 9k zipped.

This is about as far down as I can pare down the SQL:
--------------------------------
SELECT
Table1.RecordID1,
Table2.RecordID2,
Table1.FundID,
Table1.Amount1,
Table2.Amount2,
IIf([Table2].[Amount2]<>[Table1].[Amount1],True,False) AS AmountsDiffer,
Table2.IsChosen

FROM
Table1 INNER JOIN Table2 ON (Table1.FundID = Table2.FundID) AND
(Table1.ReturnDate = Table2.ReturnDate)

WHERE
(((IIf([Table2].[Amount2]<>[Table1].[Amount1],True,False))=True) AND
((Table2.IsChosen)=False));
--------------------------------

FundID's are Long, ReturnDates are DateTime.
Amounts are Double.

Table1's Data:
--------------------------------------------
FundID ReturnDate Amount1 RecordID1
1588 09/01/1991 0.0624 1
1588 12/01/1991 0.0618 2
--------------------------------------------
Table2's Data:
-------------------------------------------------
RecordID2 FundID IsChosen ReturnDate Amount2
72083 1588 Yes 09/01/1991 0.0624
97158 1588 Yes 12/01/1991 0.0618
106453 1588 No 09/01/1991 0.0624
106454 1588 No 12/01/1991 0.0618
------------------------------------------------

The amounts of 0.0618 are coming up as different, when
I expect them to come up as the same.

viz:
--------------------------------------------------------------------------
RecordID1 RecordID2 FundID Amount1 Amount2 AmountsDiffer IsChosen
2 106454 1588 0.0618 0.0618 -1 No
--------------------------------------------------------------------------

--
PeteCresswell

[Tom van Stiphout]

On Tue, 24 May 2005 21:46:14 -0700, "(PeteCresswell)" <[e-mail]>
wrote:

Sure. Send it over. My spam trap should be obvious.
One thing to consider is to use Currency for monetary values (I'm
assuming Amount* qualify.

-Tom.

I'm equi-joining two tables on a Long and a DateTime field and then
comparing an amount in one with an amount the other via an Immediate If
statement.

Problem is that for some (not all...not even most...) records, I am getting
false differences.

I know the stuff below probably looks like a rat's breakfast, but I'm at the end
of my little string on this. Similar things are happening in a couple other
queries, so I'd have to assume it's something dumb that I'm doing...but I can't
figure out what.

If anybody's got time on their hands and/or some excess curiosity, I could email
you the sample DB - it's only 9k zipped.

This is about as far down as I can pare down the SQL:
--------------------------------
SELECT
Table1.RecordID1,
Table2.RecordID2,
Table1.FundID,
Table1.Amount1,
Table2.Amount2,
IIf([Table2].[Amount2]<>[Table1].[Amount1],True,False) AS AmountsDiffer,
Table2.IsChosen

FROM
Table1 INNER JOIN Table2 ON (Table1.FundID = Table2.FundID) AND
(Table1.ReturnDate = Table2.ReturnDate)

WHERE
(((IIf([Table2].[Amount2]<>[Table1].[Amount1],True,False))=True) AND
((Table2.IsChosen)=False));
--------------------------------

FundID's are Long, ReturnDates are DateTime.
Amounts are Double.

Table1's Data:
--------------------------------------------
FundID ReturnDate Amount1 RecordID1
1588 09/01/1991 0.0624 1
1588 12/01/1991 0.0618 2
--------------------------------------------
Table2's Data:
-------------------------------------------------
RecordID2 FundID IsChosen ReturnDate Amount2
72083 1588 Yes 09/01/1991 0.0624
97158 1588 Yes 12/01/1991 0.0618
106453 1588 No 09/01/1991 0.0624
106454 1588 No 12/01/1991 0.0618
------------------------------------------------

The amounts of 0.0618 are coming up as different, when
I expect them to come up as the same.

viz:
--------------------------------------------------------------------------
RecordID1 RecordID2 FundID Amount1 Amount2 AmountsDiffer IsChosen
2 106454 1588 0.0618 0.0618 -1 No
--------------------------------------------------------------------------

[Trevor Best]

(PeteCresswell) wrote:

WHERE
(((IIf([Table2].[Amount2]<>[Table1].[Amount1],True,False))=True) AND
((Table2.IsChosen)=False));
Can you not use:

where table2.amount2 <> table1.amount1 and table2.ischosen=false

The amounts of 0.0618 are coming up as different, when
I expect them to come up as the same.

Currency or floating point?

--
[OO=00=OO]

[(PeteCresswell)]

Per Trevor Best:

Can you not use:

where table2.amount2 <> table1.amount1 and table2.ischosen=false
I was going with what the query designer came up with - but yes - and certainly
that syntax is more concise. But it still gives the same result. I'm
thinking I have some very basic conceptual problem - like which records show up
under what circumstances....i.e. the query is working correctly but I'm not
specifying correctly.

The amounts of 0.0618 are coming up as different, when
I expect them to come up as the same.

Currency or floating point?

"Decimal" per MS Access.

--
PeteCresswell

[(PeteCresswell)]

Per Tom van Stiphout:

Sure. Send it over.

Sent.
--
PeteCresswell