trigger中捕获发生错误的sql语句

举个例子，如下：（很清楚）

create or replace trigger LogErrors
  after servererror on database 

declare
  -- local variables here
  
   v_sql_out ora_name_list_t;
  v_number number;
  v_sql varchar2(500);
begin
      --捕获出错的sql语句
        v_number :=ora_sql_txt(v_sql_out);
        for i in 1..v_number loop
        v_sql:=v_sql||v_sql_out(i);
        end loop;
        dbms_output.put_line('sql:'||v_sql);

end LogErrors;