LIFO method

Question

Hello to everyone,
I need to solve a quite difficult problem, at least from my point of view :). I was given 3 tables (Entries, Consumptions, Entries_Consumptions) and I am supposed to update the Entries_Consumptions table and the Entries.LeftQuantity field according to the LIFO (Last Input - First Output) method from accounting using a trigger and eventually other functions or procedures used by the trigger. I have tried many ways and cannot find a solution for the above problem. Below is the script for the tables and also some input values.
drop table entries;
drop table consumptions;
drop table entries_consumptions;
create table entries (
IDEntry number(4)
constraint pk_entries primary key
constraint nn_entries not null,
DateEntry date,
MaterialCode number(4),
EntryQuantity number(4),
Price number(5),
LeftQuantity number(4)
create table consumptions (
IDConsumption number(4)
constraint pk_consumptions primary key
constraint nn_consumptions not null,
DateConsumption date,
MaterialCode number(4),
ConsumptionQuantity number(4)
create table Entries_Consumptions (
IDConsumption number(4),
MaterialCode number(4),
IDEntry number(4),
CorespondentQuantity number(5),
Price number(4),
constraint pk_Entries_Consumption primary key (IDConsumption, MaterialCode, IDEntry)
insert into entries values ('1000','01/12/2009','002','40','30','');
insert into entries values ('1001','10/12/2009','002','60','31','');
insert into entries values ('1002','15/12/2009','002','10','32','');
insert into entries values ('1003','21/12/2009','002','25','32','');
insert into entries values ('1004','27/12/2009','002','30','34','');
insert into consumptions values ('301','12/12/2009','002','50');
insert into consumptions values ('302','20/12/2009','002','30');
insert into consumptions values ('303','25/12/2009','002','10');
insert into consumptions values ('304','28/12/2009','002','35');
I'm asking for help to find a solution for this problem. Any suggestion will be highly appreciated.
Thank you,
Andrew.

Answer 1

http://blog.accountingcoach.com/lifo-fifo/