Re: constraint question

"eugene kim" <eugene1977_at_hotmail.com> wrote in message news:alfu81$3vd$1_at_newsreader.mailgate.org...
> hi..
> i'm a beginner sql programmer..
>
> if there's a better place to ask fundemantal sql questions like this..
> pls inform me,,
>
> my question is,
>
> create table teams(
> team_id integer primary key,
> school_id integer references schools,
> sport varchar(100),
> gender char
> );
>
> if ( school_id, sport, gender) uniquely identifies a team entity just like
> team_id can uniquely do so.
>
> is it better to have a constraint such as
> (school_id, sport, gender) unique
> in my table?
>
> well that will prevent users to insert duplicate data into table..
>
> so i guess it's better to have the constraint
> instead of forcing application programmer to check the condition..?
>
> thank you

Yes, it is because checking constraints in the application would mean the data is to be fetched to the client, and you will get a fat client. Also there is no explicit sql needed when checking declarative constraints.

Hth

--
Sybrand Bakker
Senior Oracle DBA

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