And Oracle's own documentation advises you not to create Unique indexes.
Regards
HJR
"TurkBear" <jgreco1_at_mn.rr.com> wrote in message
news:ps2ojuo8ru3p2kjnmqihgame31qu6pj8nb_at_4ax.com...
>
> In general it is a short way to create both an index and constraint..
> A Unique index is usually faster than a non-unique one the unique
constraint enforces business rules about your data and
> helps maintain 'normalized' data in a RDBMS by not allowing the accidental
insertion or creation of duplicate keys..
>
>
>
> "Cel" <cefernan_at_capgemini.fr> wrote:
>
> >so what exactly is a unique index ?
> >what's it used for ?
> >
> >"TurkBear" <jgreco1_at_mn.rr.com> a écrit dans le message news:
> >8qigju41jlklidlreeh9f480tvgmfhfk2e_at_4ax.com...
> >>
> >> Your procedure should check for the record and then do either an update
or
> >an Insert..
> >>
> >> This is not an error, it is doing exactly what a Unique constraint is
> >supposed to do..
> >>
> >> (BTW, cross-posting is not usually a good idea)
> >>
> >>
> >> "Cel" <cefernan_at_capgemini.fr> wrote:
> >>
> >> >I have a table A :
> >> >
> >> >CREATE TABLE A (
> >> >column1 VARCHAR2 (2) NOT NULL, column2 VARCHAR2 (4) NOT NULL, column3
> >> >VARCHAR2 (2) NOT NULL,
> >> >
> >> >column4 VARCHAR2 (6) NOT NULL, column5 CHAR (8) NOT NULL, column6 CHAR
> >(8),
> >> >
> >> >column7 CHAR (1), column8 CHAR (1))
> >> >
> >> >There are 5 index on the first 5 columns:
> >> >CREATE UNIQUE A_IU ON "SCHEMA".A(column1 , column2 , column3 , column4
,
> >> >column5 )
> >> >
> >> >TABLESPACE IDX_APP_A PCTFREE 5 STORAGE(INITIAL 16384 NEXT 8192
> >PCTINCREASE
> >> >0 ) ;
> >> >
> >> >I have a stored procedure which does either an INSERT :
> >> >
> >> >INSERT INTO A ( column1 , column2 , column3 , column4 , column5 ,
> >column6
> >> >, column7 , column8 )
> >> > VALUES ( val1, val2, val3, val4, val5, val6, NULL, NULL , NULL);
> >> >
> >> >or an UPDATE :
> >> >UPDATE A SET column6 = val11 AND column3 = val3 AND column4 = val4;
> >> >
> >> >Of course if the record already exists in the table,
> >> >it raises a unique constraint error.
> >> >
> >> >How do i do to avoid this error ?
> >> >thanks for your help
> >> >
> >> >
> >> >
> >> >
> >>
> >>
> >>
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>
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Received on Mon Jul 22 2002 - 15:39:38 CDT
