Re: Extending my question. Was: The relational model and relational algebra - why did SQL become the industry standard?

Lauri Pietarinen wrote:
>
>OK. Many of the questions regarding the bags<-->sets discussion seem - in
>the end - to focus on aggregates.
>
>Here is Date's and Darwen's take on aggregates:
>
>Aggregate operators are relational operators that take
>two arguments: a relation and a column name
>
>e.g. we could have AVG( EMP, SALARY) which
>would be equivalent to the SQL-statement
>
>SELECT AVG(SALARY)
> FROM EMP
>
>I can't get into all the details here but there
>there is lot's of discussion on different issues relating
>aggregates in
>Relational Database Writings 1994-1997
>(ISBN 0-201-39814-1) installments 44, 45 and 50.

I'm not much impressed by those references. The whole point of our discussion was to see how well their arguments stand up to critical examination. Since you apparently don't want to go into the specific issue that we were disussing I now get the feeling that you want to avoid that discussion.

Pity.

• Jan Hidders