March 15, 2002 at 2:33 pm
Is there a way to allow only *one* multiple value in an otherwise-unique column? In other words, is there a provision to allow for "exceptions" to a unique constraint?
For example, let's say I have a data column filled with the following rows:
Table
Chair
Lamp
I *do* want to allow multiple instances of "chair," so the following would be allowed:
Table
Chair
Chair
Lamp
Chair
However, I *do NOT* want to allow multiple values of anything else; therefore, trying to enter "table" or "lamp" would result in an error.
On a related note: I defined a unique column in a database, and I set it to allow NULLs. However, it's giving me errors because of multiple instances of NULL. Would this be a limitation of the question I stated above, or should a unique column allow multiple NULLs?
Thanks in advance for your help!
March 15, 2002 at 2:39 pm
See duplicate thread.
"Don't roll your eyes at me. I will tape them in place." (Teacher on Boston Public)
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