Re: Difference within a field between records

CREATE TABLE Foobar
(week_nbr INTEGER NOT NULL,
 tank_id INTEGER NOT NULL,
 mass INTEGER NOT NULL,
 PRIMARY KEY (week_nbr, tank_id));

 SELECT F1.week_nbr, F1.tank_id, F1.mass,

        (SELECT F2.mass 
           FROM Foobar AS F2
          WHERE F1.tank_id = F2.tank_id
            AND F1.week_nbr = F2.week_nbr + 1) - F1.mass

I am making a lot of assumptions about NULLs, keys, constraints, week numbering, etc. because you did not bother to post DDL or clear specs. Received on Mon Jan 21 2002 - 04:21:05 CET