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Home > Archive > SQL Anywhere database > August 2005 > Trigger that mimics "unique constraint" but allows duplicate NULLS
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Trigger that mimics "unique constraint" but allows duplicate NULLS
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| Ed Zapalac 2005-08-22, 11:23 am |
| I need help writing a trigger that will fire before update and before
insert. The function of the trigger is almost identical to the "unique
constraint" requirement you can place on a field, except I want to allow
duplicate nulls. I have warehouse locations that can be unused (null), but
when they are in use I don't want to allow duplication of product serial
numbers (the serial number is unique and it is not logical to have the same
piece of equipment in two places). Any assistance you can provide would be
appreciated.
Thanks,
Edward
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| Bruce Hay 2005-08-22, 1:23 pm |
| Have you tried creating a unique index on the columns, rather than defining
a uniqueness constraint or creating a trigger? The unique index will allow
nulls.
Whitepapers, TechDocs, bug fixes are all available through the iAnywhere
Developer Community at http://www.ianywhere.com/developer
"Ed Zapalac" <e.zapalac@ssss.com> wrote in message
news:4309f395@forums
-2-dub...
> I need help writing a trigger that will fire before update and before
> insert. The function of the trigger is almost identical to the "unique
> constraint" requirement you can place on a field, except I want to allow
> duplicate nulls. I have warehouse locations that can be unused (null),
but
> when they are in use I don't want to allow duplication of product serial
> numbers (the serial number is unique and it is not logical to have the
same
> piece of equipment in two places). Any assistance you can provide would
be
> appreciated.
>
> Thanks,
> Edward
>
>
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| Ed Zapalac 2005-08-22, 8:23 pm |
| That works. Thanks Bruce.
"Bruce Hay" < h_a_y@i~a~n~y~w~h~e~
r~e.c_o_m> wrote in message
news:430a00ae$1@foru
ms-2-dub...
> Have you tried creating a unique index on the columns, rather than
> defining
> a uniqueness constraint or creating a trigger? The unique index will allow
> nulls.
>
> Whitepapers, TechDocs, bug fixes are all available through the iAnywhere
> Developer Community at http://www.ianywhere.com/developer
>
> "Ed Zapalac" <e.zapalac@ssss.com> wrote in message
> news:4309f395@forums
-2-dub...
> but
> same
> be
>
>
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