This is a case of garbage in/garbage out. If your users enter more than one owner per property match with no sold date you have to catch that as a validation rule violation. You could run a DLookup("*","tblPropOwner", "PropID=" & Me.txtPropID & " And DateSold is Null")
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Bill Mosca, Founder - MS_Access_Professionals
http://www.thatlldoit.com
Microsoft Office Access MVP
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---In MS_Access_Professionals@yahoogroups.com, <jan.hertzsch@gmail.com> wrote :
I have a PROPERTY table and an OWNER table. I want to keep a history of who owned what property, when, and who is the current owner.
I was planning on using a third table with 4 fields. Property, Owner, Date Purchased, Date Sold. With the obvious relationships to the PROPERTY and OWNER tables. I had assumed a blank Date Sold field would allow me to indicate the current owner. However, I want to make sure I don't have active two Property/Owner relationships. That is, the same PROPERTY with an open Date Sold field for two owners.
I am not wedded to this design but I cannot think how I could do a validation for this on data entry.
This has to happen in databases all the time. How would you suggest I design or validate my way out of this?
Thanks
I was planning on using a third table with 4 fields. Property, Owner, Date Purchased, Date Sold. With the obvious relationships to the PROPERTY and OWNER tables. I had assumed a blank Date Sold field would allow me to indicate the current owner. However, I want to make sure I don't have active two Property/Owner relationships. That is, the same PROPERTY with an open Date Sold field for two owners.
I am not wedded to this design but I cannot think how I could do a validation for this on data entry.
This has to happen in databases all the time. How would you suggest I design or validate my way out of this?
Thanks
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