Mini Project in audit Transfer amount in bank postgresql

Create table account 

drop table if exists accounts;

create table accounts (  

   id int generated by default as identity,

    name varchar(100) not null,

    balance dec(15,2) not null,

    primary key(id)

);

insert into accounts(name,balance) values('Bob',10000);

insert into accounts(name,balance) values('Alice',10000);

Create store procedure for update balance :

create or replace procedure sp_transfer (sender int, recever int, amount  int)

language plpgsql
as
$$
begin
update accounts set balance = balance - amount    where id=sender ;
update accounts set balance = balance + amount  where id=recever ;
commit;
end
$$

Create function for update balance :

create or replace function fn_transfer()

returns trigger 
language plpgsql
as
$$
begin 
if new.balance<>old.balance then
insert into amount_audit(cust_id,c_name,t_amount,balance,datetime,status)
values (old.id,old.name,new.balance - old.balance,new.balance,current_timestamp,
   CASE WHEN new.balance - old.balance > 0 then 'Cradit' else 'Debit' end );
end if;
return new;
end
$$

Create trigger 

create  trigger tg_transfer
before update 
on accounts
for each row
execute procedure  fn_transfer()