IsNull always returns True

[nathj]

Hi,

I have a report that contains numerous sub-reports, some of which may not have any data to display. According to the Crystal KB I am supposed to set up a variable that determines if there are records and then suppress the relevant section based on that variable. All seems fine. However, when I try this it is not working.

The field tmpChild.ffchild contains 21 yet IsNull() returns True.

Here is the code in question.
If IsNull(Count({tmpChild.FFCHILD})) OR Count({tmpChild.FFCHILD}) = 0 then
SuppressChild:= TRUE
Else
SuppressChild:= FALSE;

The value in tmpchild.FFChild is 21.00. However, IsNull(Count({tmpChild.FFCHILD})) returns True as does IsNull({tmpChild.FFCHILD}).

Any ideas as to how to make this work correctly would be much appreciated.

Many thanks
Nathan Davies

 

[synapsevampire]

You're using isnull(count, not isnull, I'm sure the whitepaper didn't suggest that.

And do you mean "The value in THE COUNT OF tmpchild.FFChild is 21.00"?

Don't mix theories, a count won't be null.

Rather than chat about theory, I suggest that you post SPECIFICALLY what section you are intending to suppress.

Perhaps If IsNull({tmpChild.FFCHILD}) is what you want, or just use the count alone, hard to know from your theoretical posting.

Successful posts tend to include:

Crystal verison
Database/connectivity
Example data
Expected output

Also try to avoid subreports as they tend to slow things down.

-k

 

[nathj]

Hi,

Thanks for stopping by.

I am trying to suppress a details section that contains a sub report if the sub report data is empty. Because of the nature of the report I have to use sub reports.

The problem is, I have since discovered, that count() returns NULL when there is only one record in the table. In my previous example I was saying that the value in the field was 21, the table itself contains only 1 record. Count returns NULL and so IsNull returns True.

I have copied the code from the Crystal KB article. However, I have also come up with a much better solution for this problem. Still using sub reports I intend to use an extra data source that will control the suppression for me. If the report cursor is empty the new control table will set a flag to indicate the section should be suppressed. In this way I can do everything in the program and leave Crystal just for the display.

Thanks for stopping by and thanks for the tips. I didn't know that sub reports slowed things down. Unfortunately in this case there is very little I can do about it but I will bear it in mind for the future.

Many thanks
Nathan

 

[nathj]

I should have said above that I meant to add the required details to my forst post, but forgot, and I could not find the edit function. So just for reference:

I am running a Visual FoxPro 9 app and VFP database. The output tables are converted to fox2x as thats what Crystal will use. I am using version 8.5 of Crystal.

Cheers