Question

以下代码用于保存Menu和Item对象：

public void setMenus(List<Menu> menus) {
    mMenuDataSource.saveMenus(menus);

    for (Menu menu:menus) {
        mItemDataSource.saveItems(menu.getItems(), menu.getId());
    }
}

MenuDataSource类：

public class MenuDataSource {
    private SQLiteDatabase mDatabase;
    private MenuSQLiteHelper mHelper;
    private String[] mAllColumns = { MenuSQLiteHelper.COLUMN_ID,
            MenuSQLiteHelper.COLUMN_NAME, MenuSQLiteHelper.COLUMN_IS_ENABLED };

    private ItemDataSource mItemDataSource;

    public MenuDataSource(Context context) {
        mHelper = new MenuSQLiteHelper(context);
    }

    public void saveMenus(List<Menu> menus) {
        mDatabase = mHelper.getWritableDatabase();
        for (Menu menu : menus) {
            long menuId = mDatabase.insert(MenuSQLiteHelper.TABLE_NAME, null,
                menuToContentValues(menu));
            menu.setId(menuId);
        }
    }

    private ContentValues menuToContentValues(Menu menu) {
        ContentValues values = new ContentValues();
        values.put(MenuSQLiteHelper.COLUMN_NAME, menu.getName());
        values.put(MenuSQLiteHelper.COLUMN_IS_ENABLED, menu.isEnabled());

        return values;
    }
}

ItemDataSource：

public class ItemDataSource {
    private SQLiteDatabase mDatabase;
    private ItemSQLiteHelper mHelper;
    private String[] mAllColumns = { ItemSQLiteHelper.COLUMN_ID,
            ItemSQLiteHelper.COLUMN_NAME, ItemSQLiteHelper.COLUMN_IS_ENABLED,
            ItemSQLiteHelper.COLUMN_COST, ItemSQLiteHelper.COLUMN_COMPOSITION,
            ItemSQLiteHelper.COLUMN_COOKING_TIME, ItemSQLiteHelper.COLUMN_MENU_ID,
            ItemSQLiteHelper.COLUMN_DESCRIPTION, ItemSQLiteHelper.COLUMN_COMPOSITION };

    public ItemDataSource(Context context) {
        mHelper = new ItemSQLiteHelper(context);
    }

    public void saveItems(List<Item> items, long menuId) {
        mDatabase = mHelper.getWritableDatabase();

        for (Item item : items) {
            long itemId = mDatabase.insert(ItemSQLiteHelper.TABLE_NAME, null, itemToContentValues(item, menuId));
            Log.e("item_id", String.valueOf(itemId));
        }

        mDatabase.close();
    }

    private ContentValues itemToContentValues(Item item, long menuId) {
        ContentValues values = new ContentValues();
        values.put(ItemSQLiteHelper.COLUMN_NAME, item.getName());
        values.put(ItemSQLiteHelper.COLUMN_DESCRIPTION, item.getDescription());
        values.put(ItemSQLiteHelper.COLUMN_COMPOSITION, item.getComposition());
        values.put(ItemSQLiteHelper.COLUMN_COST, item.getCost());
        values.put(ItemSQLiteHelper.COLUMN_IS_ENABLED, item.isEnabled());
        values.put(ItemSQLiteHelper.COLUMN_COOKING_TIME, item.getCookingTime());
        values.put(ItemSQLiteHelper.COLUMN_MENU_ID, menuId);

        return values;
    }

}

MenuSQLiteHelper类：

public class MenuSQLiteHelper extends SQLiteOpenHelper {

    public static final String TABLE_NAME = "menus";

    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_NAME = "name";
    public static final String COLUMN_IS_ENABLED = "is_enabled";

    private static final String DATABASE_CREATE = "create table "
            + TABLE_NAME + "(" + COLUMN_ID + " integer primary key autoincrement, " +
            COLUMN_NAME + " text, " +
            COLUMN_IS_ENABLED + " integer);";

    public MenuSQLiteHelper(Context context) {
        super(context, DbConstants.DATABASE_NAME, null, DbConstants.DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase database) {
        database.execSQL(DATABASE_CREATE);
        Log.e("menu", "created");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.e("menu", "updated");
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}

ItemSQLiteHelper类：

public class ItemSQLiteHelper extends SQLiteOpenHelper {

    public static final String TABLE_NAME = "items";

    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_NAME = "name";
    public static final String COLUMN_DESCRIPTION = "description";
    public static final String COLUMN_COMPOSITION = "composition";
    public static final String COLUMN_COST = "cost";
    public static final String COLUMN_COOKING_TIME = "cooking_time";
    public static final String COLUMN_MENU_ID = "menu_id";
    public static final String COLUMN_IS_ENABLED = "is_enabled";

    private static final String DATABASE_CREATE = "create table " +
            TABLE_NAME + "(" + COLUMN_ID + " integer primary key autoincrement, " +
            COLUMN_NAME + " text, " +
            COLUMN_DESCRIPTION + " text, " +
            COLUMN_COMPOSITION + " text, " +
            COLUMN_COST + " integer, " +
            COLUMN_COOKING_TIME + " integer, " +
            COLUMN_MENU_ID + " integer, " +
            COLUMN_IS_ENABLED + " integer);";

    public ItemSQLiteHelper(Context context) {
        super(context, DbConstants.DATABASE_NAME, null, DbConstants.DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase database) {
        Log.e("item", "created");
        database.execSQL(DATABASE_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.e("item", "updated");
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}

正如您所看到的，代码非常简单 - 它只创建了2个表并保存了菜单和项目。但是我收到以下错误： "android.database.sqlite.SQLiteException: no such table: items: , while compiling: INSERT INTO items(composition,menu_id,cooking_time,is_enabled,cost,description,name) VALUES (?,?,?,?,?,?,?)"

但是，如果我保存没有菜单的项目，那么一切都很好。我该如何解决？谢谢。

Answer 1

请查看此answer，您会发现您不能将两个SQLiteOpenHelper类指向同一个数据库。

您可以将它们分成两个不同的数据库（通过为它们提供不同的数据库名称），但您可能要做的是将两个SQLiteOpenHelper类合并为一个（这样您以后可以运行使用这两个表的查询）。 / p>

Answer 2

一开始没有数据库文件。当您首先运行mMenuDataSource的方法时，它会发生“oncreate”，并使用表“menus”创建数据库; 然后运行mItemDataSource的方法，但是已经创建了数据库文件，所以它的“oncreate”没有发生，因此没有任何东西可以创建“items”表。

您应该在相同的“oncreate”方法中创建两个表。

Android SQLite应用程序中没有包含2个表的此类表

2 个答案: