import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;

public class DBHelper extends SQLiteOpenHelper {

 private final static String DB_NAME ="test.db";//数据库名
 private final static int VERSION = 1;//版本号

 //自带的构造方法
 public DBHelper(Context context, String name, CursorFactory factory,
   int version) {
  super(context, name, factory, version);
 }

 //为了每次构造时不用传入dbName和版本号，自己得新定义一个构造方法
 public DBHelper(Context cxt){
  this(cxt, DB_NAME, null, VERSION);//调用上面的构造方法
 }

 //版本变更时
 public DBHelper(Context cxt,int version) {
  this(cxt,DB_NAME,null,version);
 }

 //当数据库创建的时候调用
 public void onCreate(SQLiteDatabase db) {
  String sql = "create table student(" +
      "id integer primary key autoincrement," +
      "name varchar(20)," +
      "age int)";

  db.execSQL(sql);
 }

 //版本更新时调用
 public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
  String sql  = "update student ....";//自己的Update操作
  db.execSQL(sql);
 }

}

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import cn.learn.db.dao.domain.Student;
import cn.learn.db.util.DBHelper;

public class StudentDao {

 DBHelper helper = null;

 public StudentDao(Context cxt) {
  helper = new DBHelper(cxt);
 }

 /**
  * 当Activity中调用此构造方法，传入一个版本号时，系统会在下一次调用数据库时调用Helper中的onUpgrade()方法进行更新
  * @param cxt
  * @param version
  */
 public StudentDao(Context cxt, int version) {
  helper = new DBHelper(cxt, version);
 }

 // 插入操作
 public void insertData(Student stu) {
  String sql = "insert into student (name,age)values(?,?)";
  SQLiteDatabase db = helper.getWritableDatabase();
  db.execSQL(sql, new Object[] { stu.name, stu.age });
 }

 // 其它操作

}