Sqlite数据库升级

package com.example.sqliteDao;
import java.util.ArrayList;

import java.util.List;
import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;
import com.example.bean.User;

import com.example.sqlite.MySqlite;
public class SqLiteDao {

 

 private SQLiteDatabase db;
 public SqLiteDao(Context context){

  MySqlite msl=new MySqlite(context);

  db=msl.getWritableDatabase();

 }

 //添加

 public void add(String name,int num){

  db.execSQL("insert into classroom(name,num) values(?,?);", new Object[]{name,num});

 }

 //删除

 public void delete(int id){

  db.execSQL("delete from classroom where id=?;", new Object[]{id});

 }

 //修改

 public void update(String name,int id){

  db.execSQL("update classroom set name=? where id=?;", new Object[]{name,id});

 }

 public List<User> query(){

  Cursor cursor=db.rawQuery("select * from classroom ", null);

  List<User> lu=new ArrayList<User>();

  while(cursor.moveToNext()){

   lu.add(new User(cursor.getString(cursor.getColumnIndex("name")), cursor.getInt(cursor.getColumnIndex("id"))));

   

  }

  return lu;

 }

}