Make a query Count() return 0 instead of empty

Question

I have a report that tracks how long certain items have been in the database, and does so by tracking it over a series of age ranges (20-44, 45-60, 61-90, 91-180, 180+). I have the following query as the data source of the report:

SELECT DISTINCT Source.ItemName, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) > 20) AS Total, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) BETWEEN 20 AND 44) AS BTWN_20_44, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) BETWEEN 45 AND 60) AS BTWN_45_60, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) BETWEEN 61 AND 90) AS BTWN_61_90, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) BETWEEN 91 AND 180) AS BTWN_91_180, 
Count(SELECT Source.DateAdded FROM Source WHERE Int(Date()-Source.DateAdded) > 180) AS GT_180
FROM Source
GROUP BY Source.ItemName;

This query works great, except if there aren't any entries a column. Instead of returning a count of 0, an empty value is returned.

How do I get Count() to return a 0 instead of empty?

Answer 1

You can return

ISNULL(Count(......), 0)

and all should be fine - would be in MS SQL Server - but I just saw you're using Access. Since I don't know Access enough, I'm not sure this will work - can you try it?

OK - glad to see there's something similar in Access (if not exactly the same as in SQL Server).

Marc

Answer 2

Replace the Count statements with

Sum(Iif(DateDiff("d",DateAdded,Date())>=91,Iif(DateDiff("d",DateAdded,Date())<=180,'1','0'),'0')) AS BTWN_91_180,

I'm not a fan of the nested Iifs, but it doesn't look like there's any way around them, since DateDiff and BETWEEN...AND were not playing nicely.

To prune ItemNames without any added dates, the query block had to be enclosed in a larger query, since checking against a calculated field cannot be done from inside a query. The end result is this query:

SELECT *
FROM 
     (
     SELECT DISTINCT Source.ItemName AS InvestmentManager, 
     Sum(Iif(DateDiff("d",DateAdded,Date())>=20,Iif(DateDiff("d",DateAdded,Date())<=44,'1','0'),'0')) AS BTWN_20_44,
     Sum(Iif(DateDiff("d",DateAdded,Date())>=45,Iif(DateDiff("d",DateAdded,Date())<=60,'1','0'),'0')) AS BTWN_45_60,
     Sum(Iif(DateDiff("d",DateAdded,Date())>=61,Iif(DateDiff("d",DateAdded,Date())<=90,'1','0'),'0')) AS BTWN_61_90,
     Sum(Iif(DateDiff("d",DateAdded,Date())>=91,Iif(DateDiff("d",DateAdded,Date())<=180,'1','0'),'0')) AS BTWN_91_180,
     Sum(Iif(DateDiff("d",DateAdded,Date())>180,'1','0')) AS GT_180,
     Sum(Iif(DateDiff("d",DateAdded,Date())>=20,'1','0')) AS Total
     FROM Source
     WHERE CompleteState='FAILED'
     GROUP BY ItemName
     )
WHERE Total > 0;

Answer 3

Even better, use Nz() e.g.

Nz(Count(SELECT Source.DateAdded 
            FROM Source 
            WHERE Int(Date()-Source.DateAdded), 0)

This will return 0 when the result is null, or count otherwise.

Note the Nz() function is part of the Access object model and therefore only available when used within the Access user interface. If you are using the Access database engine without the Access UI (from another application via OLE DB, ODBC, etc) then you will get an error, "Undefined function 'Nz' in expression".

Answer 4

On second though (without more information) I think you are doing this query very wrong....

As I said, when I try your original query I get an error "At most one record can be returned by this subquery".

This is probably a little closer to what you want

SELECT DISTINCT Source.ItemName, 
    (SELECT count(Source.DateAdded ) FROM Source 
        WHERE Int(Date()-Source.DateAdded)> 20)  AS Total, 
    (SELECT count(Source.DateAdded ) FROM Source  
        WHERE Int(Date()-Source.DateAdded) BETWEEN 20 AND 44) AS BTWN_20_44, 
    (SELECT count(Source.DateAdded ) FROM Source  
        WHERE Int(Date()-Source.DateAdded) BETWEEN 45 AND 60) AS BTWN_45_60, 
    (SELECT count(Source.DateAdded ) FROM Source  
        WHERE Int(Date()-Source.DateAdded) BETWEEN 61 AND 90) AS BTWN_61_90, 
    (SELECT count(Source.DateAdded ) FROM Source  
        WHERE Int(Date()-Source.DateAdded) BETWEEN 91 AND 180) AS BTWN_91_180, 
    (SELECT count(Source.DateAdded ) FROM Source  
        WHERE Int(Date()-Source.DateAdded) > 180) AS GT_180
FROM Source
GROUP BY Source.ItemName;

Unless you are trying to get a count per Item name... in which case it's a little trickyier.

Answer 5

Did you ever try the Partition SQL function ? It could make your query much simpler !!!

Answer 6

hi any one know how to count the repeated values in ms-access for example

No REPEATED 98945787, 1 TIMES, 98545855, 1TIMES 56465858, 1TIMES 98945787, 2ND TIMES LIKE ABOVE EXAMPLE REPATED NUMBERS ARE WILL BE COUNT BY THIS MANY TIME ITS REPEATED. I WANT TO CREATE IN THIS MSACCESS QUERY PLEASE HELP ME IF YOU KNOW ANSWER PLEASE MAIL ME [email protected]