RE: SQL descending primary key

["Walden H. Leverich" <WaldenL@xxxxxxxxxxxxxxx>]

> > A key is about uniqueness, not access, while an index is about 
> > access, and not necessarily uniqueness.

> Basically, it seems a key - primary or unique - is not meant for 
> sorting rows for access - on the iSeries we certainly CAN use them as 
> an index, but that is not the SQL way of thinking.

Actually an index isn't about "sorting" rows either. The only thing an
index is about is performance. There is nothing in sql that _requires_
an index. You could create an entire system without ever creating an
index. Now, if you want it to perform well... :)

The _only_ way you can rely on rows being returned to you in a given
sequence is to specify the "order by" clause on the select. And since
you can order by anything in sql, regardless of the existence of an
index, you don't need an index for ordering. 

-Walden