&& opening stock table
create  cursor open_stock (dates d(8),codes c(4),products c(15),qty n(3),rate n(6,2),amount n(6,2))
insert into open_stock values({^2009-07-01},'1401','Coke 250ml',2,14.45,0)
replace all amount with qty*rate

&& purchase table
create  cursor purchase (dates d(8),codes c(4),products c(15),qty n(3),rate n(6,2),amount n(6,2))
insert into purchase values({^2009-07-02},'1401','Coke 250ml',2,15.30,0)
insert into purchase values({^2009-07-01},'1401','Coke 250ml',4,16.80,0)
insert into purchase values({^2009-07-03},'1401','Coke 250ml',6,13.25,0)
replace all amount with qty*rate

&& sale table
create  cursor sales (dates d(8),codes c(4),products c(15),qty n(3),rate n(6,2),amount n(6,2))
insert into sales values({^2009-07-03},'1401','Coke 250ml',6,0,0)
insert into sales values({^2009-07-05},'1401','Coke 250ml',3,0,0)