create or replace trigger tri_cdo_mstr_upd before insert or update of cdo_content on cdo_mstrfor each rowdeclare     var_start INT := 0;    var_end   INT := 0;    str       varchar2(4000);    --str_flag1 varchar2(255) := '';    str_flag2 varchar2(255) := '';    str_flag3 varchar2(255) := '';    var_cdo_content  varchar2(4000);begin      var_cdo_content := :new.cdo_content;     loop      if instr(var_cdo_content,str_flag1) > 0 then         var_start := instr(var_cdo_content,str_flag1);      elsif instr(var_cdo_content,str_flag2) > 0 then         var_start := instr(var_cdo_content,str_flag2);      end if;      if var_start > 0 then        var_end := instr(var_cdo_content,str_flag3);      end if;            exit when (var_start=0 or var_end=0);      if var_start > 0 and var_end > 0 then        str := substr(var_cdo_content,var_start,var_end-var_start+length(str_flag3));      end if;      var_cdo_content := replace(var_cdo_content,str);    end loop;        :new.cdo_content:=var_cdo_content;end tri_cdo_mstr_upd;