รบกวนดูโค้ด เขียน trigger ใน afterparameter มัน error

function AfterPForm return boolean is

begin

  IF (:p_acct_from IS NOT NULL and :p_acct_to IS NOT NULL) then
  	:P_ACCT_SQL :=  ' and gcc.segment2 between '''|| :p_acct_from ||''' and '''|| :p_acct_to ||'''';
  ELSE	
	:P_ACCT_SQL := '';
 END IF;
 IF (:p_cc_from IS NOT NULL and :p_cc_to IS NOT NULL) then
               :P_CC_SQL := 'and gcc.segment3  between '''|| :p_cc_from ||''' and '''|| :p_cc_to ||'''';
 ELSE
	:P_CC_SQL := '';
 END IF;
 IF (:p_int_comp_from IS NOT NULL and :p_int_comp_to IS NOT NULL) then
  	:P_INT_COMP_SQL := 'and gcc.segment4  between '''|| :p_int_comp_from ||''' and '''|| :p_int_comp_to ||'''';
 ELSE
	:P_INT_COMP_SQL := '';
 END IF;
 IF (:p_proj_from IS NOT NULL and :p_proj_to IS NOT NULL) then
  	:P_PROJ_SQL := 'and gcc.segment5  between '''||:p_proj_from ||''' and '''|| :p_proj_to ||'''';
 ELSE
	:P_PROJ_SQL := '';
 END IF;
  return (TRUE);
end;