我已经使用这个示例创建了一个数据库，我在全新安装时复制了它

http://www.reigndesign.com/blog/using-your-own-sqlite-database-in-android-applications/

我现在遇到的问题是，我现在已经对数据库进行了一些更新，而且我假设我也在构建中对主文件进行了更新，因此用户总是在新安装时获得最新版本

我有一个不同的类来处理所有的数据库调用查询语句。

我设置了这条线

private static final int DATABASE_VERSION = 5;

现在在全新安装中，数据库已正确复制，但是当查询类再次调用 databasehelper 时，将调用 onupgrade() 方法并尝试更新到最新版本，但应用程序崩溃，因为它正在尝试进行升级做不到

我的理解是以下在全新安装时设置数据库版本或者这是错误的。如果是这样，我如何为新安装设置数据库版本

public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DATABASE_VERSION);
        this.context = context;
    }

为了完整起见，这里是 onupgrade() 的示例

@Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        dbUpgrade = new DatabaseUpgrades(context);

        Log.d(DEBUG_TAG, "Calling onupgrade db");
        Log.d(DEBUG_TAG + " : " + DatabaseHelper.class.getName(),
                "Upgrading database from version " + oldVersion + " to "
                    + newVersion);

        if (oldVersion == 1) {
            Log.d(DEBUG_TAG, "Updating to Version 2");
            dbUpgrade.upgradeDB2(db);
            oldVersion++;
        }
}

询问新安装的新数据库设置为什么版本，如果不是版本 5，如何覆盖它

谢谢

最佳答案

这是正确的:

public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DATABASE_VERSION);
        /* ... */
}

我将源代码放在 getWritableDatabase() 下方，如您所见，它不会调用 onUpgrade() 除非 db 文件中的版本不等于当前的新版本您在构造函数中传递的版本(version != mNewVersion 行)。所以要么你的数据库文件没有被覆盖，要么你的新数据库中的版本号是错误的。请检查一下。

/**
 * Create and/or open a database that will be used for reading and writing.
 * Once opened successfully, the database is cached, so you can call this
 * method every time you need to write to the database.  Make sure to call
 * {@link #close} when you no longer need it.
 *
 * <p>Errors such as bad permissions or a full disk may cause this operation
 * to fail, but future attempts may succeed if the problem is fixed.</p>
 *
 * @throws SQLiteException if the database cannot be opened for writing
 * @return a read/write database object valid until {@link #close} is called
 */
public synchronized SQLiteDatabase getWritableDatabase() {
    if (mDatabase != null && mDatabase.isOpen() && !mDatabase.isReadOnly()) {
        return mDatabase;  // The database is already open for business
    }

    if (mIsInitializing) {
        throw new IllegalStateException("getWritableDatabase called recursively");
    }

    // If we have a read-only database open, someone could be using it
    // (though they shouldn't), which would cause a lock to be held on
    // the file, and our attempts to open the database read-write would
    // fail waiting for the file lock.  To prevent that, we acquire the
    // lock on the read-only database, which shuts out other users.

    boolean success = false;
    SQLiteDatabase db = null;
    if (mDatabase != null) mDatabase.lock();
    try {
        mIsInitializing = true;
        if (mName == null) {
            db = SQLiteDatabase.create(null);
        } else {
            db = mContext.openOrCreateDatabase(mName, 0, mFactory);
        }

        int version = db.getVersion();
        if (version != mNewVersion) {
            db.beginTransaction();
            try {
                if (version == 0) {
                    onCreate(db);
                } else {
                    onUpgrade(db, version, mNewVersion);
                }
                db.setVersion(mNewVersion);
                db.setTransactionSuccessful();
            } finally {
                db.endTransaction();
            }
        }

        onOpen(db);
        success = true;
        return db;
    } finally {
        mIsInitializing = false;
        if (success) {
            if (mDatabase != null) {
                try { mDatabase.close(); } catch (Exception e) { }
                mDatabase.unlock();
            }
            mDatabase = db;
        } else {
            if (mDatabase != null) mDatabase.unlock();
            if (db != null) db.close();
        }
    }
}

编辑
您可以使用以下查询检查新数据库文件中的版本:

PRAGMA user_version;

在您的情况下，它应该返回 5。

关于android - SQLITE - 设置新数据库的版本，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/7648131/