Re: Insert trigger to enforce uniqueness

In article <26ee1067.0203031743.c3da536_at_posting.google.com>, tram_e_at_hotmail.com says...
>
>Hi,
>
>Our third party application doesn't allow to create Unique indexes on
>a column.
>I want to write an insert trigger which allow nulls but no duplicate
>values on a column (peopleID column). Waht is the best way to write
>BEFORE INSERT TRIGGER for thsi kind of requirement? Please give sample

just create a unique constraint on it and be done with it. No worse for you to create a unique index then to add triggers to third party products (no better either)

It will allow NULLS and enforce uniqueness. Doing this in a trigger is fruitless unless you serialize all inserts into this table (multi-versioning, if two people insert to same value at the same time -- your trigger will never see it).

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Thomas Kyte (tkyte@us.oracle.com)             http://asktom.oracle.com/ 
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