1 创建一个员工表emp自己添加员工数据 CREATE TABLE emp id INT PRIMARY KEY -- 员工id ename VARCHAR50 -- 员工姓名 job_id INT -- 职务id mgr INT -- 上级领导 Joindate Date -- 入职日期 salary double72 -- 工资 bonus double72 -- 奖金;

以下是使用jdbc预编译对象操作数据库的代码示例：

import java.sql.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class JDBCExample {
    public static void main(String[] args) {
        // 数据库连接信息
        String url = "jdbc:mysql://localhost:3306/test";
        String username = "root";
        String password = "password";

        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            // 1. 加载数据库驱动
            Class.forName("com.mysql.jdbc.Driver");

            // 2. 建立数据库连接
            conn = DriverManager.getConnection(url, username, password);

            // 3. 修改1号数据的salary为10000
            String sql1 = "UPDATE emp SET salary = ? WHERE id = ?";
            pstmt = conn.prepareStatement(sql1);
            pstmt.setDouble(1, 10000);
            pstmt.setInt(2, 1);
            int rows1 = pstmt.executeUpdate();
            System.out.println("修改记录数：" + rows1);

            // 4. 添加一条记录
            String sql2 = "INSERT INTO emp (id, ename, job_id, mgr, Joindate, salary, bonus) VALUES (?, ?, ?, ?, ?, ?, ?)";
            pstmt = conn.prepareStatement(sql2);
            pstmt.setInt(1, 2);
            pstmt.setString(2, "John");
            pstmt.setInt(3, 2);
            pstmt.setInt(4, 1);
            pstmt.setDate(5, new java.sql.Date(System.currentTimeMillis()));
            pstmt.setDouble(6, 5000);
            pstmt.setDouble(7, 1000);
            int rows2 = pstmt.executeUpdate();
            System.out.println("添加记录数：" + rows2);

            // 5. 删除刚才添加的记录
            String sql3 = "DELETE FROM emp WHERE id = ?";
            pstmt = conn.prepareStatement(sql3);
            pstmt.setInt(1, 2);
            int rows3 = pstmt.executeUpdate();
            System.out.println("删除记录数：" + rows3);

            // 6. 查询id为1的记录，将其封装为Map集合
            String sql4 = "SELECT * FROM emp WHERE id = ?";
            pstmt = conn.prepareStatement(sql4);
            pstmt.setInt(1, 1);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                Map<String, Object> map = new HashMap<>();
                map.put("id", rs.getInt("id"));
                map.put("ename", rs.getString("ename"));
                map.put("job_id", rs.getInt("job_id"));
                map.put("mgr", rs.getInt("mgr"));
                map.put("Joindate", rs.getDate("Joindate"));
                map.put("salary", rs.getDouble("salary"));
                map.put("bonus", rs.getDouble("bonus"));
                System.out.println(map);
            }

            // 7. 查询所有记录，将其封装为List
            String sql5 = "SELECT * FROM emp";
            pstmt = conn.prepareStatement(sql5);
            rs = pstmt.executeQuery();
            List<Map<String, Object>> list = new ArrayList<>();
            while (rs.next()) {
                Map<String, Object> map = new HashMap<>();
                map.put("id", rs.getInt("id"));
                map.put("ename", rs.getString("ename"));
                map.put("job_id", rs.getInt("job_id"));
                map.put("mgr", rs.getInt("mgr"));
                map.put("Joindate", rs.getDate("Joindate"));
                map.put("salary", rs.getDouble("salary"));
                map.put("bonus", rs.getDouble("bonus"));
                list.add(map);
            }
            System.out.println(list);

            // 8. 查询所有记录，将其封装为emp对象的List集合
            String sql6 = "SELECT * FROM emp";
            pstmt = conn.prepareStatement(sql6);
            rs = pstmt.executeQuery();
            List<Emp> empList = new ArrayList<>();
            while (rs.next()) {
                Emp emp = new Emp();
                emp.setId(rs.getInt("id"));
                emp.setEname(rs.getString("ename"));
                emp.setJobId(rs.getInt("job_id"));
                emp.setMgr(rs.getInt("mgr"));
                emp.setJoindate(rs.getDate("Joindate"));
                emp.setSalary(rs.getDouble("salary"));
                emp.setBonus(rs.getDouble("bonus"));
                empList.add(emp);
            }
            System.out.println(empList);

            // 9. 查询总记录数
            String sql7 = "SELECT COUNT(*) FROM emp";
            pstmt = conn.prepareStatement(sql7);
            rs = pstmt.executeQuery();
            if (rs.next()) {
                int count = rs.getInt(1);
                System.out.println("总记录数：" + count);
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 10. 关闭数据库连接
            try {
                if (rs != null) {
                    rs.close();
                }
                if (pstmt != null) {
                    pstmt.close();
                }
                if (conn != null) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
}

class Emp {
    private int id;
    private String ename;
    private int jobId;
    private int mgr;
    private Date joindate;
    private double salary;
    private double bonus;

    // 省略getters和setters
}

请注意替换数据库连接信息，并根据自己的需求修改SQL语句和数据模型