赞
踩
2021/11/27
- //已经提供Student类的属性,补充完成该类的有参(五个参数)及无参构造方法
- public Student(){}
- public Student(String name,String pwd,int age,int grade,int rate){
- this.name=name;
- this.pwd=pwd;
- this.age=age;
- this.grade=grade;
- this.rate=rate;
- }
- //请修改该方法,并且在赋值时,课程难度只能为:高、中、低这三种之一,其余值不做任何处理。
- public void setDifficulty(String difficulty) {
- switch(difficulty){
- case "高":this.difficulty = difficulty;break;
- case "中":this.difficulty = difficulty;break;
- case "低":this.difficulty = difficulty;break;
- default :break;
- }
-
- }
- //请修改该方法,以保证打印对象时输出格式如下:(sname=zs;cname=语文;score=80)
- @Override
- public String toString() {
- return "(sname="+sname+";cname="+cname+";score="+score+")";
- }
- /**
- * 插入学生
- * @param s 学生对象
- * @return
- */
- public int add(Student s) {
- // 请补全sql语句
- String sql = "insert into `student` values (?,?,?,?,?)";
- return studentUtil.add(sql, s.getName(),s.getPwd(),s.getAge(),s.getGrade(),s.getRate());
- }
- /**
- * 查询学生总人数
- * @return 返回总人数
- */
- public int queryNum() {
- String sql = "select * from student";
- List<Student> list = studentUtil.getList(sql, Student.class);
- // 请修改以下代码,保证返回值为总人数,假设所有学生名字都不一样
- int num = list.size();
- return num;
- }
- /**
- * 查询最小年龄的学生姓名
- * @return 返回学生姓名
- */
- public String queryMinAge() {
- // 请补全sql语句
- String sql = "select `name` from `student` where age = (select min(age) from `student`)";
- Student g = studentUtil.getOne(sql, Student.class);
- return g.getName();
- }
- /**
- * 根据课程名称来查询课程
- * @return 返回课程对象
- */
- public Course queryCourse(String name) {
- // 请补全sql语句
- String sql = "select * from `course` where `name` = ?";
- return courseUtil.getOne(sql, Course.class, name);
- }
- /**
- * 根据课程名称来更新课程难度
- * @return 更新成功返回true,没有更新成功返回false
- */
- public boolean updateDifficultyByName(String name,String difficulty){
- // 请补全sql语句
- String sql = "update `course` set `difficulty` = ? where `name` = ?";
- int a = courseUtil.update(sql, difficulty, name);
- if(a>0){
- return true;
- }else{
- return false;
- }
- }
- /**
- * 查询平均成绩最高的学生姓名
- * @return 返回学生姓名
- */
- public String queryAvgMax() {
- // 请补全sql语句 select `sname` from (select `sname`,avg(`score`) as aa from `score` group by `sname`)tab1 where aa = (select max(aa) from (select `sname`,avg(`score`) as aa from `score` group by `sname`)tab1)
- //select max(aa) from (select `sname`,avg(`score`) as aa from `score` group by `sname`)tab1
- String sql = "select `sname` from (select `sname`,avg(`score`) as aa from `score` group by `sname`)tab1 where aa = (select max(aa) from (select `sname`,avg(`score`) as aa from `score` group by `sname`)tab1)";
- Score s = scoreUtil.getOne(sql, Score.class);
- return s.getSname();
- }
- // 把集合 li 中的每个成绩对象的名字取出来放进集合 s 中,并返回
- // 请补全以下代码
- for (int i = 0; i < li.size(); i++) {
- s.add(li.get(i).getSname());
- }
-
- return s;
Copyright © 2003-2013 www.wpsshop.cn 版权所有,并保留所有权利。