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Home -> Community -> Mailing Lists -> Oracle-L -> Re: adding a check condition
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Hi, Rachel
Rachel Carmichael wrote:
> Is there some new syntax that I don't know of that does a table-level check
> constraint?
>
I mean something like that
create table t1(
s1 varchar(10),
s2 varchar(10),
constraint c check (s1 <> ' ' and s2 <> ' '));
The reason table vs column, of course, is to have as little dictionary
entries as possible. I think all this consideration makes the sense ONLY when
the table is iserted-updated very frequently - i.e. appropriate part of
dictionary is effectively cached. PL/SQL will not beat constraint when the
case.
Listers, one more idea - why not NOT NULL (BTW - constraint too). It works with
'' but not with ' '.
With regards,
Vadim
>
> a single PL/SQL program, even if it has to be parsed, will be faster than
> reading the data dictionary for the constraint on every column. Check
> constraints have their functions, and I have used them. But NOT to see if
> all columns have blanks in them.
>
> Rachel
>
> >From: Vadim Gorbunov <dim_at_protek.ru>
> >Reply-To: ORACLE-L_at_fatcity.com
> >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> >Subject: Re: adding a check condition
> >Date: Tue, 13 Jun 2000 04:57:04 -0800
> >
> >
> >
> >Rachel Carmichael wrote:
> >
> > > yes it adds to the overhead! and it will affect performance on every
> >insert
> > > and update. Oracle has to get the check condition from the data
> >dictionary.
> > >
> > > since you want this check on EVERY column, it might be faster to do it
> >all
> > > at once in a before-insert/before-update trigger.
> > >
> >
> >Hi, all
> >I think, trigger is slower and more expensive than check constraint(s)
> >because
> >of PL/SQL engine is not as much efficient as Oracle core functions. One
> >table
> >level check constraint would be the most effective solution.
> >
> >Vadim Gorbunov
> >Oracle DBA
> >
> > >
> > > Rachel
> > >
> > > >From: "Anand Raman" <araman_at_india-today.com>
> > > >Reply-To: ORACLE-L_at_fatcity.com
> > > >To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
> > > >Subject: adding a check condition
> > > >Date: Mon, 12 Jun 2000 22:57:04 -0800
> > > >
> > > >Hi guys
> > > >In a database which i am desiging to prevent users from entering blank
> > > >spaces into columns i am also
> > > >adding a check condition like check column <> ' ' to almost every
> >column..
> > > >Does this add to the overhead of the table and will it have any
> >performance
> > > >effect ..
> > > >Thanx
> > > >Anand
> > > >
> > > >--
> > > >Author: Anand Raman
> > > > INET: araman_at_india-today.com
> > > >
> > > >Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
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> > > --
> > > Author: Rachel Carmichael
> > > INET: carmichr_at_hotmail.com
> > >
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> ><< dim.vcf >>
>
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> --
> Author: Rachel Carmichael
> INET: carmichr_at_hotmail.com
>
> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
> San Diego, California -- Public Internet access / Mailing Lists
> --------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
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url:www.protek.ru org:Protek;IT adr:;;;Moscow;;;RussiaReceived on Wed Jun 14 2000 - 00:40:37 CDT
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