MS Access Top 1 based on Date

I have a daily data set that has some data that is not daily - it might be weekly or bi-weekly or some other timeframe.  For data that is not daily, I need to use the most recent value in all days following until I hit a day with a new value.  I am trying to run the following query to carry a value from one day to the next if there isn't a value there for use in a daily calculation.   When I run the following, I get an "Invalid Argument to Function Error"

SELECT qryA.sample_date, qryA.flow, iif(qryA.fds is not null, qryA.fds,(SELECT TOP 1 Dupe.fds
     FROM qryA as Dupe
     WHERE Dupe.sample_date < qryA.sample_date AND Dupe.FDS Is Not Null
     ORDER BY Dupe.sample_date DESC)) AS fds_mod
FROM qryA
WHERE (qryA.sample_date Between #4/1/2013# And #5/31/2013#);

If I change the "WHERE Dupe.sample_date < qryA.sample_date" to "WHERE Dupe.sample_date < #5/16/2013#" it works.  I need to be able to run the select top 1 based on the current records date.
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sj_rodriguezAsked:
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chaauCommented:
What happens if you add an alias to the main query:
SELECT A.sample_date, A.flow, iif(A.fds is not null, A.fds,(SELECT TOP 1 Dupe.fds
     FROM qryA as Dupe
     WHERE Dupe.sample_date < A.sample_date AND Dupe.FDS Is Not Null
     ORDER BY Dupe.sample_date DESC)) AS fds_mod
FROM qryA A
WHERE (A.sample_date Between #4/1/2013# And #5/31/2013#);

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aikimarkCommented:
if qryA.fds is null, will there be a non-null qryA.sample_date for that row?
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Gustav BrockCIOCommented:
How about just pulling that fds from the dupe:

SELECT
    qryA.sample_date,
    qryA.flow,
      (select top 1
          Dupe.fds
      from
          qryA As Dupe
      where
          Dupe.sample_date <= qryA.sample_date
          and
          Dupe.fds is not null
      order by
          Dupe.sample_date desc) AS
    fds
FROM
    qryA;

/gustav
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sj_rodriguezAuthor Commented:
I tried adding an alias to the main query... got the same error.

The data set has a flow value for every day.  There is an fds value every week or so.  I need to carry the fds value forward each day until there is a new value.   (i.e., There is an fds value on 5/7/2013.  The next fds value is on 5/23/2013.  I need to have the 5/7 value returned for 5/8-5/22)

I tried pulling the fds value from the dupe query... got the same error.  If I change the where statement to have a hard coded date instead of looking at the main query row date, it works.  But then all the fds values returned are that one value and not based on the date of the row.
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aikimarkCommented:
Please try the following:
SELECT qryA.sample_date, qryA.flow, 
     iif(IsNull(qryA.fds), (SELECT TOP 1 Dupe.fds
     FROM qryA as Dupe
     WHERE Dupe.sample_date < qryA.sample_date AND Dupe.FDS Is Not Null 
     ORDER BY Dupe.sample_date DESC), qryA.fds) AS fds_mod
FROM qryA
WHERE (qryA.sample_date Between #4/1/2013# And #5/31/2013#);

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sj_rodriguezAuthor Commented:
Same error.
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aikimarkCommented:
Do you have any Null dates?
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sj_rodriguezAuthor Commented:
Nope.
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aikimarkCommented:
Can you post some sample data?

What version of Access are you using?
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sj_rodriguezAuthor Commented:
MS Access 2010.

I have attached an excel file with 2 months of data.
Sample-Data.xlsx
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aikimarkCommented:
What does qryA look like?
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sj_rodriguezAuthor Commented:
The data I attached in excel is a sample of the data from qryA.  

columns for sample_date, flow, ph, fds, tkn, etc...
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aikimarkCommented:
Do you have all the service patches applied to Access?
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sj_rodriguezAuthor Commented:
I believe so... I will check.
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aikimarkCommented:
I imported the data as table qryA in Access2007 and run the SQL I posted.  No errors.  Got the following results:
sample_date	flow	fds_mod
4/1/2013	4.2	
4/2/2013	3.08	682
4/3/2013	2.01	682
4/4/2013	2.83	682
4/5/2013	2.03	682
4/6/2013	1.54	682
4/7/2013	0	682
4/8/2013	1.52	682
4/9/2013	2.78	669
4/10/2013	1.58	669
4/11/2013	3.18	669
4/12/2013	0.07	669
4/13/2013	0	669
4/14/2013	0	669
4/15/2013	2.19	669
4/16/2013	0.81	655
4/17/2013	1.05	655
4/18/2013	2.41	655
4/19/2013	3.04	655
4/20/2013	0.52	655
4/21/2013	0	655
4/22/2013	0.91	655
4/23/2013	0.59	655
4/24/2013	0.82	655
4/25/2013	0.83	655
4/26/2013	0.12	655
4/27/2013	0	655
4/28/2013	0	655
4/29/2013	0.73	655
4/30/2013	0.19	655
5/1/2013	0.7	655
5/2/2013	0.77	655
5/3/2013	0.23	655
5/4/2013	0	655
5/5/2013	0	655
5/6/2013	0.28	655
5/7/2013	1.08	672
5/8/2013	0.66	672
5/9/2013	0.9	672
5/10/2013	0.81	672
5/11/2013	0.48	672
5/12/2013	0.13	672
5/13/2013	0.29	672
5/14/2013	0.71	672
5/15/2013	0.52	672
5/16/2013	0.65	672
5/17/2013	0.4	672
5/18/2013	0.45	672
5/19/2013	0	672
5/20/2013	0.42	672
5/21/2013	0.15	672
5/22/2013	0.75	672
5/23/2013	1	685
5/24/2013	0.52	685
5/25/2013	0.95	685
5/26/2013	0.11	685
5/27/2013	0.98	685
5/28/2013	1.85	685
5/29/2013	1.25	685
5/30/2013	0.31	685
5/31/2013	1.48	685

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Checking against the table, this seems correct.
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sj_rodriguezAuthor Commented:
Let me make my qryA into a table and try it too.
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sj_rodriguezAuthor Commented:
It works for me too from the table.  Let me re-look at my qryA query - there has to be something in there causing the problem.
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aikimarkCommented:
Please post the SQL.
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sj_rodriguezAuthor Commented:
I found the issue...  As I was getting the SQL for you, I found I had an odd join/grouping thing going on to create my qryA.  qryA combines a flow table and a quality table to get a combined dataset.  I have fixed that and then the query using the top 1 works.

Corrected SQL for qryA:

SELECT qry_qual_2.sample_date, qry_qual_2.flow, qry_qual_3.ph, qry_qual_3.fds, qry_qual_3.tkn, qry_qual_3.no3_no2, qry_qual_3.bod5, qry_qual_3.ca, qry_qual_3.k, qry_qual_3.mg, qry_qual_3.na, qry_qual_3.cl, qry_qual_3.so4, qry_qual_3.hco3, qry_qual_3.total_p
FROM qry_qual_2 LEFT JOIN qry_qual_3 ON (qry_qual_2.ww_id = qry_qual_3.ww_id) AND (qry_qual_2.sample_date = qry_qual_3.sample_date)
ORDER BY qry_qual_2.sample_date;
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sj_rodriguezAuthor Commented:
I appreciated all the help received from aikimark.
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