oracle - 具有最终记录副本的 Oracle 游标

Question

Why am getting duplicate records ? pls correct me.Thanks in Advance.

declare
  clazzes_rec clazzes%rowtype;
  cursor clazzes_cur is select * from clazzes;
begin
  if clazzes_cur%isopen then
     dbms_output.put_line('Cursor is not open,trying to Open.... ... .. .');
  end if;

  open clazzes_cur;

  dbms_output.put_line('Cursor opened :');

  loop
    fetch clazzes_cur into clazzes_rec;
      dbms_output.put_line('id:'||clazzes_rec.id||':name:'||clazzes_rec.name);
    exit  when clazzes_cur%notfound;
  end loop;

  close clazzes_cur;

end;

输出:

Cursor opened :
id:1:name:leo1
id:2:name:leo2
id:3:name:leo3
id:4:name:leo4
id:4:name:leo4

PL/SQL procedure successfully completed

Answer 1

只需交换行:

loop
 fetch clazzes_cur into clazzes_rec;
 exit  when clazzes_cur%notfound;
  dbms_output.put_line('id:'||clazzes_rec.id||':name:'||clazzes_rec.name);
end loop;

当您获取最后一条记录并尝试获取下一条 clazzes_cur%notfound 时，它会变为 true，但在它有机会退出循环之前，您将再次输出最后一条记录。