Path: utzoo!attcan!uunet!midway!ncar!elroy.jpl.nasa.gov!usc!chaph.usc.edu!aludra.usc.edu
From: ajayshah@aludra.usc.edu (Ajay Shah)
Newsgroups: comp.databases
Subject: Ease of SQL with an ugly schema
Message-ID: <10698@chaph.usc.edu>
Date: 9 Jul 90 09:07:27 GMT
Sender: news@chaph.usc.edu
Organization: University of Southern California, Los Angeles, CA
Lines: 34


I'm pretty naive of databases and SQL, and wondered how this
query would be represented using SQL:

	There is a table containing fields X Y and FLAG.  FLAG
	takes values zero or one.  One wishes to create the
	summation over the table of a variable Z where Z is defined
	as follows:

		If (flag = 0) then Z := X - Y
			else Z := X + Y

	So the query is essentially implemented by the algorithm:

		sum := 0;
		for (all records in table) do
			with current_record do
			begin
				If (flag = 0) then Z := X - Y
						else Z := X + Y
				sum := sum + Z
			end;
		writeln(sum);


	Representing this in SQL wasn't immediately obvious to
	me... can someone produce a demo?


Thankx
_______________________________________________________________________________
Ajay Shah, (213)747-9991, ajayshah@usc.edu
                              The more things change, the more they stay insane.
_______________________________________________________________________________