数据库查询学号为s003的学生比学号为s004的学生的最高分数高的课程编号和分数

好的，根据您的要求，我可以为您提供以下 SQL 查询语句来获得学号为s003的学生比学号为s004的学生的最高分数高的课程编号和分数：

SELECT Course.course_id, MAX(Score.score) AS max_score
FROM Score
INNER JOIN Course ON Score.course_id = Course.course_id
WHERE Score.student_id = 's003' OR Score.student_id = 's004'
GROUP BY Course.course_id
HAVING MAX(CASE WHEN Score.student_id = 's003' THEN Score.score END) > MAX(CASE WHEN Score.student_id = 's004' THEN Score.score END);

这个查询语句会首先从 Score 表中获取学号为 s003 或 s004 的学生的所有成绩，然后通过 INNER JOIN 连接 Course 表来获取对应的课程信息。接着，使用 GROUP BY 语句按照课程编号将成绩分组，并使用 HAVING 语句筛选出 s003 学生的最高分数比 s004 学生的最高分数高的课程。最后，使用 MAX 函数来获取每个课程的最高分数。

希望这个查询语句能够帮助到您！

相关问题

制作一个学生选课系统，系统包括学号，姓名，性别，年级，密码。课程要包括课程编号，课程名称，已选人数，可选人数，授课老师。文件CourseDB.java：单例类，模拟数据库中的课程，初始化后至少封装10门课程。文件StudentDB.java：单列类，模拟数据库中的课程，初始化后至少封装5名学生信息；文件Login.java:负责登录的业务逻辑；文件SelectCourse.java：负责选课的业务逻辑；文件MainProcess.java：负责整体业务流程；学生选课成功后，选课状态变更为“已选”，否则，课程状态变更为“可选”；学生选择“已选”课程，提示“该课程无法重复选择”；学生选课成功后，选课人数相应发生变化

好的，以下是一个基本的Java实现学生选课系统的代码：

CourseDB.java

import java.util.ArrayList;
import java.util.List;

public class CourseDB {
    private static CourseDB instance;
    private List<Course> courses;

    private CourseDB() {
        courses = new ArrayList<>();
        courses.add(new Course("C001", "Java Programming", 0, 10, "Tom"));
        courses.add(new Course("C002", "Data Structure", 0, 15, "John"));
        courses.add(new Course("C003", "Algorithm Analysis", 0, 20, "Lucy"));
        courses.add(new Course("C004", "Database Management", 0, 15, "Bob"));
        courses.add(new Course("C005", "Web Development", 0, 12, "Alice"));
        courses.add(new Course("C006", "Mobile Application Development", 0, 8, "Jack"));
        courses.add(new Course("C007", "Artificial Intelligence", 0, 20, "David"));
        courses.add(new Course("C008", "Computer Networks", 0, 18, "Sarah"));
        courses.add(new Course("C009", "Operating System", 0, 15, "Mike"));
        courses.add(new Course("C010", "Computer Graphics", 0, 10, "Lisa"));
    }

    public static CourseDB getInstance() {
        if (instance == null) {
            instance = new CourseDB();
        }
        return instance;
    }

    public List<Course> getCourses() {
        return courses;
    }

    public void setCourses(List<Course> courses) {
        this.courses = courses;
    }
}

StudentDB.java

import java.util.ArrayList;
import java.util.List;

public class StudentDB {
    private static StudentDB instance;
    private List<Student> students;

    private StudentDB() {
        students = new ArrayList<>();
        students.add(new Student("S001", "张三", "男", "大一", "123456"));
        students.add(new Student("S002", "李四", "女", "大二", "123456"));
        students.add(new Student("S003", "王五", "男", "大三", "123456"));
        students.add(new Student("S004", "赵六", "女", "大四", "123456"));
        students.add(new Student("S005", "陈七", "男", "大一", "123456"));
    }

    public static StudentDB getInstance() {
        if (instance == null) {
            instance = new StudentDB();
        }
        return instance;
    }

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

Login.java

import java.util.Scanner;

public class Login {
    public static Student login() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入学号：");
        String id = scanner.nextLine();
        System.out.println("请输入密码：");
        String password = scanner.nextLine();

        StudentDB studentDB = StudentDB.getInstance();
        for (Student student : studentDB.getStudents()) {
            if (student.getId().equals(id) && student.getPassword().equals(password)) {
                return student;
            }
        }
        return null;
    }
}

SelectCourse.java

import java.util.Scanner;

public class SelectCourse {
    public static void selectCourse(Student student) {
        CourseDB courseDB = CourseDB.getInstance();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请选择课程（输入课程编号，输入0退出）：");
            for (Course course : courseDB.getCourses()) {
                System.out.println(course.getCourseId() + " " + course.getCourseName() + " " +
                        course.getTeacher() + " " + course.getSelectedNum() + "/" + course.getTotalNum());
            }
            String courseId = scanner.nextLine();
            if (courseId.equals("0")) {
                break;
            }
            Course selectedCourse = null;
            for (Course course : courseDB.getCourses()) {
                if (course.getCourseId().equals(courseId)) {
                    selectedCourse = course;
                    break;
                }
            }
            if (selectedCourse == null) {
                System.out.println("输入的课程编号不存在，请重新输入！");
                continue;
            }
            if (selectedCourse.getSelectedNum() >= selectedCourse.getTotalNum()) {
                System.out.println("该课程已选满，请重新选择！");
                continue;
            }
            if (student.getSelectedCourses().contains(selectedCourse)) {
                System.out.println("该课程已选过，请重新选择！");
                continue;
            }
            selectedCourse.setSelectedNum(selectedCourse.getSelectedNum() + 1);
            student.getSelectedCourses().add(selectedCourse);
            System.out.println("选课成功！");
        }
    }
}

MainProcess.java

public class MainProcess {
    public static void main(String[] args) {
        Student student = Login.login();
        if (student != null) {
            System.out.println("欢迎" + student.getName() + "登录选课系统！");
            SelectCourse.selectCourse(student);
        } else {
            System.out.println("学号或密码错误，登录失败！");
        }
    }
}

Course.java

public class Course {
    private String courseId;
    private String courseName;
    private int selectedNum;
    private int totalNum;
    private String teacher;

    public Course(String courseId, String courseName, int selectedNum, int totalNum, String teacher) {
        this.courseId = courseId;
        this.courseName = courseName;
        this.selectedNum = selectedNum;
        this.totalNum = totalNum;
        this.teacher = teacher;
    }

    public String getCourseId() {
        return courseId;
    }

    public void setCourseId(String courseId) {
        this.courseId = courseId;
    }

    public String getCourseName() {
        return courseName;
    }

    public void setCourseName(String courseName) {
        this.courseName = courseName;
    }

    public int getSelectedNum() {
        return selectedNum;
    }

    public void setSelectedNum(int selectedNum) {
        this.selectedNum = selectedNum;
    }

    public int getTotalNum() {
        return totalNum;
    }

    public void setTotalNum(int totalNum) {
        this.totalNum = totalNum;
    }

    public String getTeacher() {
        return teacher;
    }

    public void setTeacher(String teacher) {
        this.teacher = teacher;
    }
}

Student.java

import java.util.ArrayList;
import java.util.List;

public class Student {
    private String id;
    private String name;
    private String gender;
    private String grade;
    private String password;
    private List<Course> selectedCourses;

    public Student(String id, String name, String gender, String grade, String password) {
        this.id = id;
        this.name = name;
        this.gender = gender;
        this.grade = grade;
        this.password = password;
        this.selectedCourses = new ArrayList<>();
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getGrade() {
        return grade;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public List<Course> getSelectedCourses() {
        return selectedCourses;
    }

    public void setSelectedCourses(List<Course> selectedCourses) {
        this.selectedCourses = selectedCourses;
    }
}

利用java代码：系统至少应包括以下信息： 学生信息：学号、姓名、性别、年级、密码 课程信息：课程编号、课程名称、已选人数、可选人数、授课教师。 (1) 文件CourseDB.java：单例类，模拟数据库中的课程，初始化后至少封装10门课程； （2）文件StudentDB.java：单列类，模拟数据库中的课程，初始化后至少封装5名学生信息； （3）文件Login.java:负责登录的业务逻辑； （4）文件SelectCourse.java：负责选课的业务逻辑； （5）文件MainProcess.java：负责整体业务流程； （6）学生选课成功后，选课状态变更为“已选”，否则，课程状态变更为“可选”；学生选择“已选”课程，提示“该课程无法重复选择”； （7）学生选课成功后，选课人数相应发生变化；

好的，以下是利用Java代码实现上述系统的示例：

CourseDB.java

import java.util.ArrayList;
import java.util.List;

public class CourseDB {
    private static CourseDB instance;
    private List<Course> courses;

    private CourseDB() {
        courses = new ArrayList<>();
        courses.add(new Course("C001", "Java基础", 0, 2, "张三"));
        courses.add(new Course("C002", "Java高级", 0, 3, "李四"));
        courses.add(new Course("C003", "数据库基础", 0, 2, "王五"));
        courses.add(new Course("C004", "操作系统", 0, 2, "赵六"));
        courses.add(new Course("C005", "计算机网络", 0, 2, "钱七"));
        courses.add(new Course("C006", "数据结构与算法", 0, 2, "孙八"));
        courses.add(new Course("C007", "软件工程", 0, 2, "周九"));
        courses.add(new Course("C008", "人工智能", 0, 2, "吴十"));
        courses.add(new Course("C009", "计算机组成原理", 0, 2, "郑一"));
        courses.add(new Course("C010", "编译原理", 0, 2, "钱二"));
    }

    public static CourseDB getInstance() {
        if (instance == null) {
            instance = new CourseDB();
        }
        return instance;
    }

    public List<Course> getCourses() {
        return courses;
    }

    public void setCourses(List<Course> courses) {
        this.courses = courses;
    }
}

StudentDB.java

import java.util.ArrayList;
import java.util.List;

public class StudentDB {
    private static StudentDB instance;
    private List<Student> students;

    private StudentDB() {
        students = new ArrayList<>();
        students.add(new Student("S001", "张三", "男", "大一", "123456"));
        students.add(new Student("S002", "李四", "女", "大一", "234567"));
        students.add(new Student("S003", "王五", "男", "大二", "345678"));
        students.add(new Student("S004", "赵六", "女", "大二", "456789"));
        students.add(new Student("S005", "钱七", "男", "大三", "567890"));
    }

    public static StudentDB getInstance() {
        if (instance == null) {
            instance = new StudentDB();
        }
        return instance;
    }

    public List<Student> getStudents() {
        return students;
    }

    public void setStudents(List<Student> students) {
        this.students = students;
    }
}

Login.java

import java.util.Scanner;

public class Login {
    public static Student login() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入学号：");
        String id = scanner.nextLine();
        System.out.println("请输入密码：");
        String password = scanner.nextLine();

        for (Student student : StudentDB.getInstance().getStudents()) {
            if (student.getId().equals(id) && student.getPassword().equals(password)) {
                System.out.println("登录成功！");
                return student;
            }
        }

        System.out.println("学号或密码错误，请重新输入！");
        return null;
    }
}

SelectCourse.java

import java.util.Scanner;

public class SelectCourse {
    public static void selectCourse(Student student) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请选择要选的课程编号：");
        String courseId = scanner.nextLine();

        for (Course course : CourseDB.getInstance().getCourses()) {
            if (course.getId().equals(courseId)) {
                if (course.getSelectedNum() < course.getLimitNum()) {
                    if (student.getSelectedCourses().contains(course)) {
                        System.out.println("该课程已经选择过了！");
                    } else {
                        student.getSelectedCourses().add(course);
                        course.setSelectedNum(course.getSelectedNum() + 1);
                        System.out.println("选课成功！");
                    }
                } else {
                    System.out.println("该课程已经选满！");
                }
                return;
            }
        }

        System.out.println("没有找到该课程！");
    }
}

MainProcess.java

public class MainProcess {
    public static void main(String[] args) {
        Student student = Login.login();
        if (student != null) {
            System.out.println("欢迎您，" + student.getName() + "！");

            while (true) {
                System.out.println("请选择要进行的操作：");
                System.out.println("1. 选课");
                System.out.println("2. 查看已选课程");
                System.out.println("3. 退出");
                int choice = Integer.parseInt(System.console().readLine());

                if (choice == 1) {
                    SelectCourse.selectCourse(student);
                } else if (choice == 2) {
                    System.out.println("您已经选了以下课程：");
                    for (Course course : student.getSelectedCourses()) {
                        System.out.println(course.getName());
                    }
                } else if (choice == 3) {
                    System.out.println("成功退出系统！");
                    break;
                } else {
                    System.out.println("无效的选择！");
                }
            }
        }
    }
}

以上是一个简单的选课系统的Java代码示例，其中实现了学生登录、选课、查看已选课程等功能。注意，这只是一个示例代码，实际应用中可能需要更多的功能和优化。