import java.sql.*;public class AccEmpl{        public static void main(String[] args){        //对象变量说明        Connection con;  //数据库连接对象（代表与某一数据库的连接）        Statement stmt;  //语句对象（可接受和执行一条SQL语句）        ResultSet rs;    //结果集对象（保存查询返回的结果）        String sql;                //加载数据库驱动程序        DriverManager.registerDriver(new com.mysql.jdbc.driver);        //建立一个与数据库的连接        con = DriverManager.getConnection("jdbc:mysql:employee");        //创建一个statement对象        stmt = con.createStatement();                System.out.println("--------查询所有职工 ，按出生年月排序---------");        //执行查询        rs = stmt.executeQuery("SELECT * FROM emp ORDER BY birthday");        while(rs.next()){            System.out.print(rs.getString("ename") + "    ");            System.out.println(rs.getDate("birthday"));        }                System.out.println("-----统计并显示各部门职工数-----");        sql = "SELECT departmentNo, COUNT(*) FROM emp Group By departmentNo";        rs = stmt.executeQuery(sql);        while(rs.next()){            System.out.print(rs.getInt(1) + "    ");            System.out.println(rs.getInt(2));        }                System.out.println("----------插入一条职工记录------------");        sql = "INSERT INTO emp VALUES('e01','Lin','male','1990-01-22',1000)";        stmt.executeUpdate(sql);                System.out.println("-----------修改职工的工资----------");        sql = "UPDATE emp SET sal=sal+? WHERE eno = ?";        PreparedStatement ps = con.prepareStatement(sql);        ps.setInt(1, 200);        ps.setString(2, "e10");        ps.executeUpdate();                con.commit();     //提交修改        con.close();      //结束一个会话周期    }}