有关onUpgrade方法的android问题 [英] Question about onUpgrade method android

问题描述

我发表在Android Market的应用程序，现在我想提出一个新的版本与数据库中的变化。现在的问题是，我的版本已发布应用程序的具有此onUpgrade方法：

  @覆盖
    公共无效onUpgrade（SQLiteDatabase _db，诠​​释_oldVersion，诠释_newVersion）{
    Log.w（TaskDBAdapter，从版本升级+
    _oldVersion +到+
    _newVersion +，这将销毁所有旧数据）;
    //删除旧表。
    _db.execSQL（DROP TABLE IF EXISTS+ DATABASE_TABLE_1）;
    _db.execSQL（DROP TABLE IF EXISTS+ DATABASE_TABLE_2）;
    //创建一个新的。
    的onCreate（_db）;
    }
 

由于我想添加一个新表，我知道，我必须作出一些改变这里保持数据的我已经和previous版本创建的表。那么，什么onUpgrade方法会被调用，从旧的或新的.apk文件。我可以不断的从表中的数据？请告诉我。 感谢ü提前。

解决方案

  

那么，什么onUpgrade方法会被调用，从旧的或新的.apk文件。

这是新的.apk文件。老走了，在这一点上。

  

我可以不断地从表中的数据？

您必须code你的，你保留你需要包括根据需要旧数据的数据这样的方式升级。

I have an application published in the android market, and now I want to make a new version with changes in the database. The problem is, my version of the app that is already published has this onUpgrade method:

    @Override
    public void onUpgrade(SQLiteDatabase _db, int _oldVersion, int _newVersion) {
    Log.w("TaskDBAdapter", "Upgrading from version " +
    _oldVersion + " to " +
    _newVersion + ", which will destroy all old data");
    // Drop the old table.
    _db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_1);
    _db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE_2);
    // Create a new one.
    onCreate(_db);
    }

Because I want to add a new table, I know that I have to make some changes here to keep the data from the tables I already created with the previous version. So what onUpgrade method will be called, from the old or from the new .apk. Can I keep the data from the tables? Please let me know. Thank u in advance.

解决方案

So what onUpgrade method will be called, from the old or from the new .apk.

From new .apk. Old one is gone at this point.

Can I keep the data from the tables?

You have to code your upgrade in such a way that you retain data that you need including old data as required.

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