Crystal Reports Null parameters

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luisbap Newbie Joined: 19 Feb 2010 Online Status: Offline Posts: 5	Topic: Null parameters Posted: 19 Feb 2010 at 4:46am
	Hello, I have a report with 3 different parameters: Date A Date B Date C The user, in another applications must choose one of these dates, but only one. What is happening is that the other 2 dates must have something. How can I allow the other 2 parameters to be left blank? Thanks in advance
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lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 19 Feb 2010 at 6:52am
	depends on how the report is structured. The other dates can be NULL and then when you filter the data, you can determine which date to use and what it means. If you are getting the data from a stored proc, all of the logic would go in the proc. or you could pass the date chosen and the type of date, since the date must signify something. The blank dates, typically, would be given a NULL value and you would work around them. If they are needed, you could reassign their value based on whether or not they are NULL. As you can tell, there are many ways to deal with only 1 date out of 3 being set. It's up to you and the report to determine which method best suits your needs.
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luisbap Newbie Joined: 19 Feb 2010 Online Status: Offline Posts: 5	Posted: 19 Feb 2010 at 7:15am
	Thanks for your answer Lockwelle, let me put the question in another way (I'm kind of newbie, so please be patiente). I'm using CRXI r2 with an Oracle database (no store procedures) and I'm talking about "optional parameters". When the user runs the report he can choose from DateA and/or DateB and/or DateC (among other parameters). What is happening is that all fields are mandatory and I can't left any date blank or the report will not run. I tried to use a default value for dates and in 'Select Expert" used a formula like the one below for all 3 dates: If {?DateA} = '31-12-2099' then True else {table.DateA} = {?DateA} I left 2 dates with 'default values' and the DateC with a correct date. It should return all records with the DateC, but it is returning all records without any filter. What went wrong?
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lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 19 Feb 2010 at 7:27am
	well, the true means to include the record, and if you have 3 sets of the above if statement, it will probably take the last one as the 'final' determination. I would try something like: local booleanvar da; local booleanvar db; local booleanvar dc; If {?DateA} = '31-12-2099' then da := True else da := ({table.DateA} = {?DateA}); repeat for all dates... if da and db and db then true else false;//this if statement, as it is the 'return' value can be abbreviated to : da and db and dc (I think) HTH
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DBlank Moderator Joined: 19 Dec 2008 Online Status: Offline Posts: 9053	Posted: 19 Feb 2010 at 7:31am
	I think and easier approach here would to use 3 parenthed OR statements joined by ANDS (credit to Hilfy on this): ({?DateA} = '31-12-2099' or {table.DateA} = {?DateA}) AND ({?DateB} = '31-12-2099' or {table.DateB} = {?DateB}) AND ({?DateC} = '31-12-2099' or {table.DateC} = {?DateC}) Edited by DBlank - 19 Feb 2010 at 7:32am
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lockwelle Moderator Joined: 21 Dec 2007 Online Status: Offline Posts: 4374	Posted: 19 Feb 2010 at 7:39am
	yes, that would definitely work, but there are times I keep it simple for both my head, and so that others can see it simplied. I am sure that I would do something similar.
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luisbap Newbie Joined: 19 Feb 2010 Online Status: Offline Posts: 5	Posted: 19 Feb 2010 at 7:46am
	Thanks DBlank, that easier approach worked out fine. Thanks also to lockwelle for the patiente and time spent. Best regards for both of you
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