Re: Finding out about indexes from system tables

"Stan Brown" <stanb_at_panix.com> wrote in message news:9j9k58$20f$1_at_panix2.panix.com...
> In <9j8q96$e51$1_at_sun-cc204.lut.ac.uk> "Andrew Hardy"
 <nobody_at_spam.from.news.AdvanticaTech.com> writes:
>
>
> >"Stan Brown" <stanb_at_panix.com> wrote in message
> >news:9j7tcl$f7q$1_at_panix3.panix.com...
> >> In <tle416qk5brk10_at_beta-news.demon.nl> "Sybrand Bakker"
 <postbus_at_sybrandb.demon.nl> writes:
> >>
> >>
> >> >"Stan Brown" <stanb_at_panix.com> wrote in message
> >> >news:9j71i1$bpg$1_at_panix6.panix.com...
> >> >> In <9j6ope$sf9$1_at_sun-cc204.lut.ac.uk> "Andrew Hardy"
> >> >>
> >> >> Thanks for the _FAST_ response.
> >> >>
 

> >> >The first column in the constraint is in position 1 and so on.
> >>
> >>
> >> OK, but is this significant? If so, how?
 

> >Tables can have multiple columns making up the primary key, the position
> >indicates the order of the columns in the key. This is mainly of interest
> >when using the indexes e.g. making queries that have best chance of using
> >the index on the primary key.
>
>
> Ah, thnaks for the clarification.
>
> Doesn't sound useful for what I am doing, so I'll just remove that from
 the
> select.
>
> Thanks for the help on this.
>
>

It might be significant in that the columns with position greater than 1 will only be "key" if all preceding position columns in the index are also used (ie for a column with position = 2 to be "key" the column with position number 1 in the index needs to be used too)

Regards,

Ian Brown Received on Sun Jul 22 2001 - 07:03:03 CDT