rem This trigger fires on an insert into the HOLDING table
rem It checks that there is sufficient cash for the purchase

create or replace trigger check_cash
  after insert on holding
  for each row
  declare 

	  tempcash number(8,2);

  begin
    select cash into tempcash
      from portfolio
      where portfoliono = :new.portfoliono;

    if :new.numbershares * :new.purchaseprice > tempcash
      then  raise_application_error(-20001,'Insufficient cash in portfolio');
    end if;

  end;
/