| check constraint [message #374578] |
Tue, 19 June 2001 15:00  |
Bonnie Melanson
Messages: 3
Registered: April 2001
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Junior Member |
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I have a check constraint as follows:
check (column_name in ('Y',null))
I only want to allow either null or 'Y' entries, however the database will allow ANY entry. How do I allow only a 'Y' or a null value?????
Thanks!
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| Re: check constraint [message #374581 is a reply to message #374578] |
Tue, 19 June 2001 16:54  |
Andrew again...
Messages: 270
Registered: July 2000
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Senior Member |
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Actually it's not necessary to specify null as it will be allowed using this: (column_name = 'Y')
for clarity though, I'd change it to indicate the null:
(column_name = 'Y' or column_name is null)
To extend it:
(column_name in ('Y', 'N') or column_name is null)
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