Problem with a simple Crystal 10 report

Question

Help please!!
I am writing what should be a simple report in Crystal 10 which is acting oddly.
The report is built on 3 tables which sit on a SQL database and are linked through ODBC views. The tables are property, referral and incident and the property table is the one that exists in all cases. All three have a Property ID and the other two tables are linked to the property table through two full outer join connections. A property can have a referral or an incident or both.
I just want to create a report which lists all the unique properties which have a referral or an incident which has been created within a particular timescale.
The filter I am using is:
{est_property.est_address_postalcode} = "AB12 5NX" and
(({est_referral.CreatedOn}>={?Start date}) and ({est_referral.CreatedOn}<={?End date}))
or
(({Incident.CreatedOn}>={?Start date})and ( {Incident.CreatedOn}<={?End date} ))
Note the 'AB12 5NX' bit is just to speed the testing process up as the databases that I am querying are large.
The version I am running is 10.0.0.533 although I am currently (very slowly) downloading SP6.
Thanks,
John

Answer 1

I have made some progress on this. I think the problem is because the filter fails when the tables it is querying have Nulls in them.
I have just tried building the filter again with an "if the 'created on' field in the referral table is NULL then just query on the incident table" type of query:
if isnull({est_referral.CreatedOn})=FALSE then
    {est_property.est_address_postalcode} = "AB12 5NX" and
    ({?Start date}<={est_referral.CreatedOn} and {est_referral.CreatedOn}<={?End date})
    or
    {est_property.est_address_postalcode} = "AB12 5NX" and
    ({?Start date}<={Incident.CreatedOn}and {Incident.CreatedOn}<={?End date} )
else
    {est_property.est_address_postalcode} = "AB12 5NX" and
    ({?Start date}<={Incident.CreatedOn}and {Incident.CreatedOn}<={?End date} )
This seems to work but seems to be very heavy on the processing. It would also require a very complex bit of coding when I start building the proper query which actually requires four sub-tables to be queried rather than ust two!
So still help required!
Thanks.