create table Org9 (
oid integer primary key,
title varchar(20)
);

create table Bill9 (
bid integer primary key,
bdate timestamp,
oid integer references Org9 (oid)
);

create table BillContent9 (
beid integer primary key,
bid integer references Bill9 (bid),
good varchar(20),
quantity float,
price money
);

create table Payment9 (
pid integer primary key,
bid integer references bill9 (bid),
pdate timestamp,
psum money
);


insert into mOrg values (1, 'QWERTY');
insert into mOrg values (2, 'ABC');

insert into Billcontent9 values (1, 1 , 'pen', 10, 10);
insert into Bill9 values (2, 2 , 'trouser', 20, 20);
insert into Bill9 values (3, 3 , 'pencil', 30, 30);
insert into Bill9 values (4, 4 , 'bricks', 40, 40);
insert into Bill9 values (5, 5 , 'markers', 50, 50);

insert into payment9 values (1,1,'01.01.01',100);
insert into payment9 values (2,2,'02.02.02',400);
insert into payment9 values (3,3,'03.03.03',900);
insert into payment9 values (4,4,'04.04.04',0);
insert into payment9 values (5,5,'05.05.05',700);

select good, quantity, price, quantity*price as total from billcontent9 where bid=3

select bid, title from Bill9 inner join Org9 using (oid)

select bid, title as org, quantity*price as total from Bill9 inner join Org9 using (oid) inner join billcontent9 using(bid)