数据库版本升级的DBHelper

public class DBHelper extends SQLiteOpenHelper {
    private static int CURRENTVERSION = 3;

    public DBHelper(Context context) {
        super(context, "qianfeng.db", null, CURRENTVERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.d("google_lenve_fb", "onCreate: -----");
        db.execSQL("CREATE TABLE IF NOT EXISTS USER (_id INTEGER PRIMARY KEY AUTOINCREMENT,NAME)");
        //解决用户不是从第一个版本开始安装的问题
        onUpgrade(db, 1, CURRENTVERSION);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.d("google_lenve_fb", "onUpgrade: ");
        //解决用户跳跃安装问题
        switch (oldVersion) {
            //App升级到2.0时数据库更新代码
            case 1:
                db.execSQL("CREATE TABLE IF NOT EXISTS PERSON (_id INTEGER PRIMARY KEY AUTOINCREMENT,NAME)");
                //添加Person表
                //App升级到3.0时数据库更新代码
            case 2:
                //添加一个Food表
                db.execSQL("CREATE TABLE IF NOT EXISTS FOOD (_id INTEGER PRIMARY KEY AUTOINCREMENT,NAME)");
            case 3:
            case 4:
                break;
        }
    }
}