Re: 2 overlapping indexes

On Fri, 25 Jan 2002 09:39:39 -0000, Norman Dunbar <Norman.Dunbar_at_lfs.co.uk> wrote:

>I must be missing the point here :
>
>id A,B,C are unique then surely A,B,C,D *must* also be unique if the
>columns are in that order.

Record 1 ABCD = X 1 Y 2
Record 2 ABCD = X 1 Y 3

ABCD is unique but ABC is not. If you put a unique index on ABCD then you do not enforce ABC uniqueness. I think the guy wants to enforce unique constrant AND speed up retrieval of ABCD record.

M Received on Fri Jan 25 2002 - 09:47:15 CST