here is my tables{

drop table room;
create table room(
room_no integer not null,
catagori varchar(20) not null,
quality varchar(20) not null,
price integer not null,
primary key(room_no)
);

set serveroutput on;
create or replace procedure room_av(
roomno room.room_no%type,
catagoris room.catagori%type,
qua room.quality%type,
pri room.price%type) is
begin
insert into room (room_no,catagori,quality,price) values (roomno,catagoris,qua,pri);
commit;
end room_av;
/
begin
room_av(102,'single','2nd_class',200);
room_av(103,'single','2nd_class',200);
room_av(104,'single','2nd_class',200);
room_av(105,'single','2nd_class',200);
room_av(202,'single','1st_class',300);
room_av(203,'single','1st_class',300);
room_av(204,'single','1st_class',300);
room_av(205,'single','1st_class',300);
room_av(302,'double','2nd_class',250);
room_av(303,'double','2nd_class',250);
room_av(304,'double','2nd_class',250);
room_av(305,'double','2nd_class',250);
room_av(402,'double','1st_class',400);
room_av(403,'double','1st_class',400);
room_av(404,'double','1st_class',400);
room_av(405,'double','1st_class',400);
room_av(406,'double','1st_class',400);


end;
/

drop table customer_info;

create table customer_info(
first_name varchar(20) not null,
last_name varchar(20) not null,
room_no integer not null,
catagori varchar(20) not null,
quality varchar(20) not null,
price integer not null,
date_open date not null,
primary key(room_no)
);

set serveroutput on;

--TRIGGER SECTION
create or replace trigger cust_room
before INSERT ON customer_info
for each row
declare
var customer_info.room_no%type;


BEGIN
var:=0;
var:=chcek1(:new.room_no);
if var!=0 then
SELECT catagori, quality, price
INTO :new.catagori, :new.quality, :new.price
FROM room
WHERE room_no=:new.room_no;
delete from room where room_no=:new.room_no;

elsif var=0 then
dbms_output.put_line('The room is not available');
end if;
END cust_room;
/
show errors

--FUNCTION SECTION

create or replace function check1(var number) return integer is
var1 integer;

begin
var1:=0;
select room_no into var1 from room where room_no=var;
return var1;
end;
/

i an facing problem with the trigger. plz give me a solution how i can do this