--显式游标------------------------loop循环declare   cursor test_cursor is select * from dept;  test_ dept%rowtype;--也可写为test_ test_cursor%rowtype;【此时test_cursor被看做一个结果集?】begin  if test_cursor%isopen     then close test_cursor;  end if;  open test_cursor;  loop       fetch test_cursor into test_;       exit when test_cursor%notfound;       dbms_output.put_line(test_.deptno);  end loop;  dbms_output.put_line(test_cursor%rowcount);  close test_cursor;end;--隐式游标------------------------for循环declare   cursor test_cursor is select * from dept;  --test_ test_cursor%rowtype;--这一段可忽略，游标变量在for循环中可直接使用，可不需要定义begin  for test_ in test_cursor    loop        dbms_output.put_line(test_.loc);    end loop;end;/*注：    for游标可不定义游标类型变量    for后接的就是游标类型变量*/          --DML(update,insert,delete)begin  update test_trans01 set b=111 where a=‘a‘;  if sql%rowcount<>0 then    dbms_output.put_line(sql%rowcount||‘行被更新！‘);  end if;end;--强类型ref游标----------------------declare  type test_cursor is ref cursor return test_trans01%rowtype;  test_ test_cursor;  test__ test_%rowtype;begin  open test_ for select * from test_trans01;  loop       fetch test_ into test__;       exit when test_%notfound;       dbms_output.put_line(test__.a);  end loop;  close test_;end;--弱类型ref游标----------------------declare  type test_cursor is ref cursor;  test_ test_cursor;  --test__ test_%rowtype;【这样应用会报错】  test__ dept%rowtype;begin  open test_ for select * from dept;  loop       fetch test_ into test__;       exit when test_%notfound;       dbms_output.put_line(test__.dname);  end loop;  close test_;end;--应用实例------------------------for update/delete【用于修改或删除表中数据】declare      cursor test_cursor is select * from test_trans01 for update;--begin  for test_ in test_cursor    loop      dbms_output.put_line(test_.a);      if test_.a=‘a‘ then        update test_trans01 set b=1111 where current of test_cursor;        dbms_output.put_line(test_.a||‘被更新!‘);      else null;      end if;    end loop;end;--带参数的显示游标--暂时未发现可用之处，或许可用在复杂的语句块中，接收条件判定生成的参数，但讲参数直接写在where后是一样的效果。。？declare    cursor test_cursor(dd number :=2) is select * from test_trans01 where b>dd;--参数变量不能限定范围    test_ test_cursor%rowtype;begin    open test_cursor;    loop         fetch test_cursor into test_;         exit when test_cursor%notfound;         dbms_output.put_line(test_.b);    end loop;    close test_cursor;end;