Oracle 查找每个客户的订单数

我试图将每个客户的订单数量显示为dbms_输出。put_行，但计数不正确…我做错了什么

declare
  t_order       number;
  cust_id       customer.c_id%type;
  orders_cid    orders.c_id%type;
  cust_first    customer.c_first%type;
  cust_last customer.c_last%type;

  cursor c is
    select distinct(customer.c_id),
           customer.c_first,
           customer.c_last,
           orders.c_id
      from customer
      join orders
        on customer.c_id = orders.c_id;
begin
  dbms_output.put_line('AZ SPORTS OUTSTANDING ORDERS');
  dbms_output.put_line('FIRST   LAST    TOTAL');
  dbms_output.put_line('NAME    NAME    ORDERS');

  OPEN C;
  LOOP
    FETCH C INTO CUST_ID, CUST_FIRST, CUST_LAST, ORDERS_CID;
    EXIT WHEN C%NOTFOUND;

    IF CUST_ID=ORDERS_CID THEN
      select count(distinct(orders.c_id))
        into t_order
        from orders
        join customer
          on orders.c_id = customer.c_id

      DBMS_OUTPUT.PUT_LINE(TO_CHAR(CUST_FIRST) || ' ' ||
                           TO_CHAR(CUST_LAST)  || ' ' ||
                           TO_CHAR(T_ORDER));
    END IF;
  END LOOP;

  CLOSE C;
END;
/

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每个客户的订单数一直显示为5，这不是正确答案。

在我看来，您需要在

选择计数…

语句中使用WHERE子句-可能类似于

WHERE orders.C\u ID=orders\u CID和customer.C\u ID=CUST\u ID

。试试看它是如何工作的

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