/**
 * @author liulp
 */
public class MysqLite extends sqliteOpenHelper {

    private volatile sqliteDatabase db;

    //建表语句 此部分只是用户第一次安装的时候会在oncreate方法中调用 
    //请注意CREATE部分不要做任何修改 所有的数据库修改都应该在 update_sql中进行
    String CREATE[] = new String[] { "create table " + TB_USER + " (tid  integer primary key,name varchar(50));","Create table " + TB_USER_REPORT + "( tid integer primary key,uid integer,score integer);",};

    //升级部分的
    private static UpDateGrades[] updategrades = new UpDateGrades[] {

    new UpDateGrades() {

	@Override
	public void doupDateGrade(sqliteDatabase db) {
	    // TODO Auto-generated method stub
	    db.execsql("create table " + TB_USER_REPORT + " (tid  integer primary key,uid interger,score interger);");
	}
    },};

    private static final String DBNAME = "popo";

    //
    public static final String TB_USER = "user";
    public static final String TB_USER_REPORT = "user_report";

    String TAG = "sqlITE";

    private static volatile MysqLite MysqLite = null;

    private MysqLite(Context context) {

	super(context,DBNAME,null,updategrades.length + 1);
	Log.v("MysqLite"," version=" + updategrades.length + 1);
	db = getWritableDatabase();
	updategrades = null;
	CREATE = null;

    }

    public static MysqLite instance(Context context) {
	if (MysqLite == null) {
	    synchronized (MysqLite.class) {
		if (MysqLite == null)
		    MysqLite = new MysqLite(context);
	    }
	}

	return MysqLite;
    }

    public sqliteDatabase getsqliteDatabase() {
	if (db == null) {
	    synchronized (this) {
		if (db == null)
		    db = getWritableDatabase();
	    }

	} else {
	    if (db.isOpen() == false) {
		synchronized (this) {
		    if (db.isOpen() == false) {
			db = null;
			db = getWritableDatabase();
		    }
		}
	    }
	}
	return db;

    }

    /**
     * 执行创建 数据库语句
     */
    @Override
    public void onCreate(sqliteDatabase db) {
	// TODO Auto-generated method stub
	Log.v(TAG,"MyDBHelper onCreate");
	for (String sql : CREATE) {
	    db.execsql(sql);
	}
    }
    
    //执行升级语句 
    @Override
    public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion) {
	// TODO Auto-generated method stub
	Log.v(" Version","oldVersion=" + oldVersion + ",newVersion=" + newVersion);
	for (int i = oldVersion; i < newVersion; i++) {
	    updategrades[i - 1].doupDateGrade(db);
	}
    }
    
    //升级语句接口
    interface UpDateGrades {
	void doupDateGrade(sqliteDatabase db);
    };

}

主要修改时把升级操作改成了一个借口方法，这样可以实现更复杂的需求分析，并且多个修改语句可以在一个方法中执行，版本号可以和我们发布的App版本比较更贴近。