It is true that a,b,c is unique, then abcd is unique as well. However
on the other hand, if you make abcd unique instead, then you will
allow unwanted data in your database. So you need think before you
decide which one you want to choose.
Norman Dunbar <Norman.Dunbar_at_lfs.co.uk> wrote in message news:<4$--$%%%_$$_%-_$-$@news.noc.cabal.int>...
> Niall wrote :
>
> >> Like Norman I can't for the life of me see the point of adding col4
> as the
> >> statement is that the first three columns are unique. Unless I have
> misread
> >> the OP of course.
>
> No, Niall, we are correct, the original poster wrote :
>
> >> I have a table with column A, B, C, D and E. The data is unique on
> A,
> >> B and C so I create a unique index on that. Now I would also like to
> >> create a non-unique index on A, B, C and D.
>
> But, we know A,B,C is unique, so D cannot make them now non-unique -
> unless he is using SQL Server :o)
>
> ------------------------------------------------------------------------
> -----
> Norman Dunbar EMail: Norman.Dunbar_at_LFS.co.uk
> Database/Unix administrator Phone: 0113 289 6265
> Fax: 0113 289 3146
> Lynx Financial Systems Ltd. URL: http://www.Lynx-FS.com
> ------------------------------------------------------------------------
> -----
>
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