create table test123 as (unit varchar2(5),qty varchar2(25));

insert into test123('ABC','10,40,50');

insert into test123('PQR','20,30,40,10');

insert into test123('XYZ','20,10,70');

create or replace restrict_sum
after insert or update of qty on test123
	for each row
	declare
	v_sum number;
	v_unit varchar2(15);
	begin
	select x.unit,sum(substr(x.qty,
					INSTR (',' ||x.qty, ',', 1, n),
					INSTR (x.qty|| ',', ',', 1, n) - INSTR ( ',' ||x.qty, ',', 1, n))) into v_unit,v_sum
	from(
		select unit,qty,max(length(qty) - length(replace(qty,',',''))) over (partition by unit) + 1 num from test123) x,
		(select level n from dual connect by level < 1000) y
	where n <= x.num
	group by x.unit;
	
	if ( v_sum <> 100 ) then
		RAISE_APPLICATION_ERROR (-20202,PLS ENTER THE CORRECT VALUE);
	END IF;
	
END;