create table p_imp (
  pi_edid number(20),
  p_sync varchar2(30)
);
create table temp_tab (
  t_fname varchar2(255),
  t_lname varchar2(255),
  t_sync  varchar2(30),
  t_ref_no varchar2(255)
);
create table p_code(
  pc_fname varchar2(255),
  pc_lname varchar(255),
  pc_edid number(20)
);
 
insert into p_imp values (12,'123456');
insert into p_imp values (30,'7890');
insert into p_imp values (70,'6356');
 
insert into temp_tab values ('John','Smith','123456','500');
insert into temp_tab values ('Mary','Aaron','7890','100');
insert into temp_tab values ('Lewis','Staff','6356','');
 
insert into p_code values ('Tim','Henry',12);
insert into p_code values ('Keith','Bullock',30);
insert into p_code values ('Robert','Clark',70);
 
After the update, p_code should be:
 
'John','Smith',12
'Mary','Aaron',30
'Robert','Clark',70