1.rs.first()、rs.last()、rs.next()、rs.getRow()

import java.sql.*;
public class Conn {
        String driver = "com.mysql.jdbc.Driver";
        String dbName = "test";
        String userName = "root";
        String passwrod = "admin";
        String url = "jdbc:mysql://localhost:3306/" + dbName;
        String sql="select * from student";
        ResultSet rs ;
        
        public ResultSet MyConn(){
            try {
                //加载驱动
                Class.forName(driver);
                //获取链接
                Connection conn = DriverManager.getConnection(url, userName,passwrod);
                //执行sql语句，存放结果集
                PreparedStatement ps = conn.prepareStatement(sql);
                rs = ps.executeQuery();
            } catch (Exception e) {e.printStackTrace();}
            return rs;
       }
}

import java.sql.*;
public class Select {
    public static void main(String[] args) throws SQLException {
        Conn dsh=new Conn();
        ResultSet rs=dsh.MyConn();
        
       //共几条记录
        rs.last(); //移到最后一行   
        int rowCount = rs.getRow(); //得到当前行号，也就是记录数   
        rs.beforeFirst(); //如果还要用结果集，就把指针再移到初始化的位置
        System.out.println("共"+rowCount+"条记录");
        
     //逐条输出    
        while(rs.next()){
        System.out.println(rs.getString("sname")+" "+rs.getString("spass"));
        /*或者rs.getString(1)+" "+rs.getString(2)*/
        }
        
    //第一条是
        rs.first();//将光标移动到第一条
        System.out.println("第一条是："+rs.getString("sname")+" "+rs.getString("spass"));
        
    //最后一条是
        rs.last();//将光标移动到第一条
        System.out.println("最后一条是："+rs.getString("sname")+" "+rs.getString("spass"));
    }

}