常用数据库中，实现分页功能的查询语句；

package com.inba.maya.DBConnection;

import java.util.*;
import java.sql.*;
import com.inba.maya.page.*;

public class FruitDao {
    private Connection conn;
    private PreparedStatement ps;
    private ResultSet rs;
    
    public FruitDao() throws Exception{
        conn=DBConnection.GetConnection();
    }
    
    //这个方法是用来获取总页数的，与下面的获取每页内容没有联系。
    public int getPage(int pagesize) throws Exception{
        //用coun(*)获取当前表的条数，注意返回的只有一行数据，并且是整数；
        String sql="select count(*) from Fruit";
        ps=conn.prepareStatement(sql);
        rs=ps.executeQuery();
        //那么rs.next()必然会指向下一个
        rs.next();
        //因为整数除整数必然是个整数，所以要乘以1.0变成小数，然后用Math.ceil获取 大于或者等于 当前数的 最小整数值；
        int pageCount=(int)Math.ceil(1.0*rs.getInt(1)/pagesize);
        return pageCount;
    }
    
    //输入两个参数，pagenum是第几页；pagesize是每页的行数
    public ArrayList<Fruit> Select(int pagenum, int pagesize) throws Exception{
        //定义一个当前要获取的类的类型的数组；
        ArrayList<Fruit> list=new ArrayList<Fruit>();
        //mysql的分页语句；
        String sql="select * from Fruit limit ?,?";
        ps=conn.prepareStatement(sql);
        ps.setInt(1, (pagenum-1)*pagesize);
        ps.setInt(2, pagesize);
        rs=ps.executeQuery();
        //如果rs.next是true，首先把要赋值的类实例化，那么通过while循环将每个字段元素赋值到相应的类的变量中，
        while(rs.next()){
            Fruit f=new Fruit();
            f.setIds(rs.getString(1));
            f.setName(rs.getString(2));
            f.setPrice(rs.getDouble(3));
            f.setNumbers(rs.getInt(5));
            f.setSource(rs.getString(4));
            f.setImages(rs.getString(6));
            
            //把每次循环f的值，都存放到数组list中；
            list.add(f);
        }
        //最后返回出去
        return list;
    }
}

package com.inba.maya.Dao;
import java.util.*;
import java.sql.*;
public class DBConnection {

       //oracle加载驱动
    public static String qd="oracle.jdbc.driver.OracleDriver";
       //oracle链接数据库
    public static String url="jdbc:oracle:thin:@localhost:1521:ORCL";
    public static String user="gmh";
    public static String password="602477126";
    
    public static Connection GetConnection() throws Exception{
        Class.forName(qd);
        Connection conn=DriverManager.getConnection(url, user, password);
        return conn;
    }
}

package com.inba.maya.Dao;

import java.util.*;
import java.sql.*;
import com.inba.maya.Dao.*;
import com.inba.maya.page.*;

public class CouserDao {
    private Connection conn;
    private PreparedStatement ps;
    private ResultSet rs;
    
    public CouserDao() throws Exception{
        conn=DBConnection.GetConnection();
    }
    
    public int GetPage(int pagesize) throws Exception{
        String sql="select count(*) from COUSER";
        ps=conn.prepareStatement(sql);
        rs=ps.executeQuery();
        rs.next();
        int page=(int)Math.ceil(1.0*rs.getInt(1)/pagesize);
        return page;
    }
    public ArrayList<Couser> Select(int pagesize, int pagenum) throws SQLException{
        ArrayList<Couser> list=new ArrayList<Couser>();
        
        //oracle的分页语句
        String sql="select * from (select a.*, rownum ro from (select * from COUSER) a) where ro between ? and ?";
        ps=conn.prepareStatement(sql);
        ps.setInt(1, (pagenum-1)*pagesize+1);
        ps.setInt(2, (pagenum-1)*pagesize+pagesize);
        rs=ps.executeQuery();
        while(rs.next()){
            Couser f=new Couser();
            f.setCon(rs.getString(1));
            f.setCname(rs.getString(2));
            f.setTon(rs.getString(3));
            
            list.add(f);
        }
        return list;
    }
    
}