通过JDBC相关的API实现学生成绩的添加、修改、查询、统计等功能，采用图形界面，数据库采用MySQL，写出相关的sql代码

以下是一个使用Java JDBC和MySQL数据库实现学生成绩的添加、修改、查询、统计等功能的示例代码，包含了图形界面和相关的SQL代码。

先创建一个名为`student`的MySQL数据库，其中包含一个名为`score`的表，该表包含以下字段：`id`(int, 自增主键), `name`(varchar(20)), `math_score`(int), `english_score`(int), `chinese_score`(int)。

SQL代码：

CREATE DATABASE student;

USE student;

CREATE TABLE score (
  id INT NOT NULL AUTO_INCREMENT,
  name VARCHAR(20) NOT NULL,
  math_score INT NOT NULL,
  english_score INT NOT NULL,
  chinese_score INT NOT NULL,
  PRIMARY KEY (id)
);

Java代码：

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.table.DefaultTableModel;

public class ScoreManager extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    private JTextField idField, nameField, mathField, englishField, chineseField;
    private JButton addButton, modifyButton, deleteButton, queryButton, statButton;
    private DefaultTableModel tableModel;
    private JTable table;

    public ScoreManager() {
        super("学生成绩管理系统");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(800, 600);
        setLocationRelativeTo(null);

        JPanel inputPanel = new JPanel();
        inputPanel.setLayout(new FlowLayout());
        inputPanel.add(new JLabel("学号:"));
        idField = new JTextField(10);
        inputPanel.add(idField);
        inputPanel.add(new JLabel("姓名:"));
        nameField = new JTextField(10);
        inputPanel.add(nameField);
        inputPanel.add(new JLabel("数学成绩:"));
        mathField = new JTextField(10);
        inputPanel.add(mathField);
        inputPanel.add(new JLabel("英语成绩:"));
        englishField = new JTextField(10);
        inputPanel.add(englishField);
        inputPanel.add(new JLabel("语文成绩:"));
        chineseField = new JTextField(10);
        inputPanel.add(chineseField);

        addButton = new JButton("添加");
        addButton.addActionListener(this);
        inputPanel.add(addButton);

        modifyButton = new JButton("修改");
        modifyButton.addActionListener(this);
        inputPanel.add(modifyButton);

        deleteButton = new JButton("删除");
        deleteButton.addActionListener(this);
        inputPanel.add(deleteButton);

        queryButton = new JButton("查询");
        queryButton.addActionListener(this);
        inputPanel.add(queryButton);

        statButton = new JButton("统计");
        statButton.addActionListener(this);
        inputPanel.add(statButton);

        add(inputPanel, BorderLayout.NORTH);

        tableModel = new DefaultTableModel(new Object[][]{}, new String[]{"学号", "姓名", "数学成绩", "英语成绩", "语文成绩"}) {
            private static final long serialVersionUID = 1L;

            @Override
            public boolean isCellEditable(int row, int column) {
                return false;
            }
        };
        table = new JTable(tableModel);
        JScrollPane scrollPane = new JScrollPane(table);
        scrollPane.setPreferredSize(new Dimension(780, 480));
        add(scrollPane, BorderLayout.CENTER);
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == addButton) {
            addScore();
        } else if (e.getSource() == modifyButton) {
            modifyScore();
        } else if (e.getSource() == deleteButton) {
            deleteScore();
        } else if (e.getSource() == queryButton) {
            queryScore();
        } else if (e.getSource() == statButton) {
            statScore();
        }
    }

    private void addScore() {
        String name = nameField.getText();
        if (name.isEmpty()) {
            JOptionPane.showMessageDialog(this, "请输入姓名");
            return;
        }

        String mathScore = mathField.getText();
        if (!isNumber(mathScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的数学成绩");
            return;
        }

        String englishScore = englishField.getText();
        if (!isNumber(englishScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的英语成绩");
            return;
        }

        String chineseScore = chineseField.getText();
        if (!isNumber(chineseScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的语文成绩");
            return;
        }

        try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student?user=root&password=root&useSSL=false");
             PreparedStatement stmt = conn.prepareStatement("INSERT INTO score (name, math_score, english_score, chinese_score) VALUES (?, ?, ?, ?)", Statement.RETURN_GENERATED_KEYS)) {
            stmt.setString(1, name);
            stmt.setInt(2, Integer.parseInt(mathScore));
            stmt.setInt(3, Integer.parseInt(englishScore));
            stmt.setInt(4, Integer.parseInt(chineseScore));

            int affectedRows = stmt.executeUpdate();

            if (affectedRows > 0) {
                try (ResultSet rs = stmt.getGeneratedKeys()) {
                    if (rs.next()) {
                        int id = rs.getInt(1);

                        Object[] row = {id, name, mathScore, englishScore, chineseScore};
                        tableModel.addRow(row);
                        table.setModel(tableModel);

                        JOptionPane.showMessageDialog(this, "添加成功");
                    }
                }
            } else {
                JOptionPane.showMessageDialog(this, "添加失败");
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
            JOptionPane.showMessageDialog(this, "添加失败");
        }
    }

    private void modifyScore() {
        String id = idField.getText();
        if (!isNumber(id)) {
            JOptionPane.showMessageDialog(this, "请输入正确的学号");
            return;
        }

        String name = nameField.getText();
        if (name.isEmpty()) {
            JOptionPane.showMessageDialog(this, "请输入姓名");
            return;
        }

        String mathScore = mathField.getText();
        if (!isNumber(mathScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的数学成绩");
            return;
        }

        String englishScore = englishField.getText();
        if (!isNumber(englishScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的英语成绩");
            return;
        }

        String chineseScore = chineseField.getText();
        if (!isNumber(chineseScore)) {
            JOptionPane.showMessageDialog(this, "请输入正确的语文成绩");
            return;
        }

        try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student?user=root&password=root&useSSL=false");
             PreparedStatement stmt = conn.prepareStatement("UPDATE score SET name = ?, math_score = ?, english_score = ?, chinese_score = ? WHERE id = ?")) {
            stmt.setString(1, name);
            stmt.setInt(2, Integer.parseInt(mathScore));
            stmt.setInt(3, Integer.parseInt(englishScore));
            stmt.setInt(4, Integer.parseInt(chineseScore));
            stmt.setInt(5, Integer.parseInt(id));

            int affectedRows = stmt.executeUpdate();

            if (affectedRows > 0) {
                int row = table.getSelectedRow();
                if (row != -1) {
                    tableModel.setValueAt(id, row, 0);
                    tableModel.setValueAt(name, row, 1);
                    tableModel.setValueAt(mathScore, row, 2);
                    tableModel.setValueAt(englishScore, row, 3);
                    tableModel.setValueAt(chineseScore, row, 4);
                    table.setModel(tableModel);

                    JOptionPane.showMessageDialog(this, "修改成功");
                }
            } else {
                JOptionPane.showMessageDialog(this, "修改失败");
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
            JOptionPane.showMessageDialog(this, "修改失败");
        }
    }

    private void deleteScore() {
        int row = table.getSelectedRow();
        if (row == -1) {
            JOptionPane.showMessageDialog(this, "请选择要删除的记录");
            return;
        }

        int id = (int) tableModel.getValueAt(row, 0);

        try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student?user=root&password=root&useSSL=false");
             PreparedStatement stmt = conn.prepareStatement("DELETE FROM score WHERE id = ?")) {
            stmt.setInt(1, id);

            int affectedRows = stmt.executeUpdate();

            if (affectedRows > 0) {
                tableModel.removeRow(row);
                table.setModel(tableModel);

                JOptionPane.showMessageDialog(this, "删除成功");
            } else {
                JOptionPane.showMessageDialog(this, "删除失败");
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
            JOptionPane.showMessageDialog(this, "删除失败");
        }
    }

    private void queryScore() {
        String id = idField.getText();
        String name = nameField.getText();

        String sql = "SELECT * FROM score WHERE 1 = 1";

        if (isNumber(id)) {
            sql += " AND id = " + id;
        }

        if (!name.isEmpty()) {
            sql += " AND name LIKE '%" + name + "%'";
        }

        try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student?user=root&password=root&useSSL=false");
             PreparedStatement stmt = conn.prepareStatement(sql);
             ResultSet rs = stmt.executeQuery()) {
            tableModel.setRowCount(0);

            while (rs.next()) {
                int idValue = rs.getInt("id");
                String nameValue = rs.getString("name");
                int mathScore = rs.getInt("math_score");
                int englishScore = rs.getInt("english_score");
                int chineseScore = rs.getInt("chinese_score");

                Object[] row = {idValue, nameValue, mathScore, englishScore, chineseScore};
                tableModel.addRow(row);
            }

            table.setModel(tableModel);
        } catch (SQLException ex) {
            ex.printStackTrace();
            JOptionPane.showMessageDialog(this, "查询失败");
        }
    }

    private void statScore() {
        String sql = "SELECT AVG(math_score), AVG(english_score), AVG(chinese_score), SUM(math_score), SUM(english_score), SUM(chinese_score) FROM score";

        try (Connection conn = DriverManager.getConnection("jdbc:mysql://localhost/student?user=root&password=root&useSSL=false");
             PreparedStatement stmt = conn.prepareStatement(sql);
             ResultSet rs = stmt.executeQuery()) {
            if (rs.next()) {
                double mathAvg = rs.getDouble(1);
                double englishAvg = rs.getDouble(2);
                double chineseAvg = rs.getDouble(3);
                int mathSum = rs.getInt(4);
                int englishSum = rs.getInt(5);
                int chineseSum = rs.getInt(6);

                JOptionPane.showMessageDialog(this, "数学平均分：" + mathAvg + "\n英语平均分：" + englishAvg + "\n语文平均分：" + chineseAvg + "\n数学总分：" + mathSum + "\n英语总分：" + englishSum + "\n语文总分：" + chineseSum);
            }
        } catch (SQLException ex) {
            ex.printStackTrace();
            JOptionPane.showMessageDialog(this, "统计失败");
        }
    }

    private boolean isNumber(String str) {
        try {
            Integer.parseInt(str);
            return true;
        } catch (NumberFormatException ex) {
            return false;
        }
    }

    public static void main(String[] args) {
        new ScoreManager().setVisible(true);
    }
}