Re: Is relational theory irrelevant?

Very good points.
In development we call this "syntactic sugar". As a developer I'm responsible to implement orthogonality (i.e. supply RANK() OVER()), howvere, said education gap ,plus the complexity coming out of the optimizer strongly encourages "shorthands" for the most common constraucts.

Let me defend my position :-)
In the latest version of DB2 we increased orthogonality by allowing INSERT, UPDATE and DELETE in the FROM clause. I.e. we declare these operators to return sets.
One of our competitors took a different approach and allows "multi-table-insert" to address a specific customer problem. Multi-table insert is shorter to type, but less powerful. It will be interesting to see when customers force us to pull even with that competitor despite us having equivalent functionality.

Cheers
Serge

-- 
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab