2021年1+X大数据Java答案

2021/10/30

步骤二

public  Member() {	
	}
	public  Member(String name,String pwd,float score,int rank) {
		this.name = name;
		this.pwd = pwd;
		this.score = score;
		this.rank = rank;
	}

步骤三

//请修改该方法，并且在赋值时，商品数量不能超过100
	public void setNum(int num) {
		if(num <= 100){
			this.num = num;
		}
	}

步骤四

/**
	 * 使用全局变量： sdf，将字符串转换为java.util.Date类型并返回
	 * 注意，不能声明任何形式的异常抛出，否则测试用例无法通过
	 * @param stringDate
	 * @return
	 */
	public static Date convertFromStringToDate(String stringDate) {
		// 补全代码：
		Date date = null;
		try {
			date = sdf.parse(stringDate);
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		return date;
	}

步骤五

/**
	 * 使用全局变量： sdf，将日期转换成字符串
	 * @param date 需要被转换的日期
	 * @return 转换之后的字符串形式的日期
	 */
	public static String convertFromDateToString(Date date) {
		// 补全或替换代码
		String str1 = sdf.format(date);
		return str1;
	}

步骤六

/**
	 * 查询所有商品中价钱最贵的商品名称 
	 * @return 返回商品名称
	 */
	public String queryExpensiveGoods() {
                // 请补全sql语句
                String sql = "select `name` from `goods` where `price` = (select max(`price`) from `goods`)";
                Goods g = goodsUtil.getOne(sql, Goods.class);
                return g.getName();
        }

步骤七

 /** 每个list里都有商品名称、数量和单价
	 * 查询所有商品的总价值金额
	 * @return 返回所有商品的总价值金额
	 */
	public double querySum() {
                String sql = "select * from goods";
                double sum = 0;
                List<Goods> list = goodsUtil.getList(sql, Goods.class);
                for (Goods goods : list) {
                        // 请补全代码
                       sum+=goods.getNum()*goods.getPrice();
                }
                return sum;
        }

步骤九

/**
	 * 根据会员的积分来更新会员的等级
	 * 0<=score<100分，等级为0
	 * 100<=score<200分，等级为1
	 * 200<=score<300分，等级为2
	 * 300<=score<400分，等级为3
	 * 400<=score<500分，等级为4
	 * 500<=score分，等级为5
	 * @return
	 */
	public void updateRank() {
                // 请补全sql语句
                String sql = "update `member` set `rank` = (case when score between 0 and 99 then 0 "+
                                                                "when score between 100 and 199 then 1 "+
                                                                "when score between 200 and 299 then 2 "+
                                                                "when score between 300 and 399 then 3 "+
                                                                "when score between 400 and 499 then 4 "+
                                                                "when score>=500 then 5 end"+
                ")";
                memberUtil.update(sql); 
        }

步骤十

/**
	 * 查询一共有多少笔订单
	 * @return 返回订单数量
	 */
	public int queryNum() {
                String sql = "select * from `order`;";
                List<Order> o = orderUtil.getList(sql, Order.class); 
                Set<Integer> s = new HashSet<Integer>();
                for (Order order : o) {
                        // 请补全语句
                        s.add(order.getId());
                }
                return s.size();
        }

步骤十一

/**
	 * 查询消费金额最多的人
	 * @return 返回会员名称select `name` from `member` where 
	 */
	public String queryMax() {
                // 请补全sql语句
                String sql = "SELECT `mname` from (SELECT `mname`,sum(`num`*`price`) as aa  from `order` GROUP BY `mname` ) tab1 where aa = (SELECT max(aa) from (SELECT sum(`num`*`price`) as aa  from `order` GROUP BY `mname`) tab1)";
                Order o = orderUtil.getOne(sql, Order.class); 
                return o.getMname();
        }