Re: user defined column functions?

lennart_at_kommunicera.umea.se (Lennart Jonsson) wrote in message news:<6dae7e65.0204111440.5db5a39c_at_posting.google.com>...
> Are there any discussions, plans, etc. for userdefined column functions in future
> SQL versions (or do they already exist somewhere and I'm not looking hard
> enough)? I'm thinking of the possability to define functions like product,
> char_concat, etc. Any thoughts?

Hi Lennart,

You might be interested to learn that there is a product called Dataphor (evaluation version can be downloaded from www.alphora.com) which implements user defined column functions.

However, the language is not SQL, but "D4" and it is implements the ideas presented in Date's and Darwen's 3rd manifesto. It also has updateable views, domains, constraints, etc...

It can be used as a front end for SQL-databases.

Here is an example of a user defined column function in "D4":

	create aggregate operator ConcatString(AValue : string) : string
		initialization
			begin
                                var i : integer := 0;
				var LString : String := "";
			end
		aggregation
			begin
                                
				LString := LString + AValue;
			end
		finalization
			begin
				Result := LString;
			end;

Lauri Pietarinen Received on Sun Apr 28 2002 - 21:27:03 CEST