Question

TEH 我正在尝试使用SQLite数据库。不幸的是，在我的onCreate方法上，我的数据库永远不会被创建，崩溃任何人都可以帮助我。我得到的错误是：没有这样的表：firstdatabase。

这是我的MySQLiteHelper类：

    public class MySQLiteHelper  extends SQLiteOpenHelper {


    //Database instance
    //private static MySQLiteHelper sInstance;

    //Database name

    private static final String DATABASE_NAME = "TestDB";

    //Table name
    private static final String TABLE_NAME = "firstdatabase";
    //column names of the table
    private static final String KEY_ID = "id";
    private static final String KEY_ISBN = "isbn";
    private static final String KEY_INGREDIENTS = "ingredients";

    //Database Version
    private static final int DATABASE_VERSION = 2;

    // Log TAG for debugging purpose
    private static final String TAG = "SQLiteAppLog";

    //Method that will ensure only one instance of the database is created.
   /* public static synchronized MySQLiteHelper getsInstance(Context context){
        if(sInstance == null){
            sInstance = new MySQLiteHelper(context.getApplicationContext());
        }
        return sInstance;
    }
    */

    // Constructor
    public MySQLiteHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        Log.d(TAG, "Inside SQLITEHELPER METHOD()");
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        //SQLite statement to create a table called 'TestDB'.
        String CREATE_PROTOTYPE_TABLE = "CREATE TABLE " + TABLE_NAME + "("
                + KEY_ID + " INTEGER PRIMARY KEY," + KEY_ISBN + " TEXT,"
                + KEY_INGREDIENTS + " TEXT" + ")";

        Log.d(TAG, "DB created");
        db.execSQL(CREATE_PROTOTYPE_TABLE);
        //Log.d(TAG, "DB created");

    }

    // onUpdate() is invoked when you upgrade the database scheme.
    // Don’t consider it seriously for the sample app.
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Drop older prototype table if existed
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);

        this.onCreate(db);
    }

    public void addIngredientsToTable(Product product){

        Log.d(TAG, "adding ingredients to table");
        SQLiteDatabase db =  this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(KEY_ISBN, product.getIsbn());
        values.put(KEY_ISBN, product.getIngredients());

        db.insert(TABLE_NAME,null, values);
        db.close();
    }

    //Method to get the ingredients list based on the isbn passed in.
    public ArrayList<String> getIngredients(String isbn){
        ArrayList<String> ingredientList = new ArrayList<String>();
        String isbnPassedIn = isbn;

        String query = "SELECT isbn, ingredients FROM " + TABLE_NAME + " WHERE isbn = " + isbnPassedIn;

        //Getting instance to a readable database
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery(query, null);

        if(cursor.moveToFirst()){
            do{
                ingredientList.add(cursor.getString(1));
                ingredientList.add(cursor.getString(2));
            }while (cursor.moveToFirst());

        }
        Log.d(TAG, "Inside getIngredients()");
        return ingredientList;
    }


    //Method to get all the list of products in the datbase.
    public ArrayList<Product> getAllProducts(){
        ArrayList<Product> productList = new ArrayList<Product>();

        String selectQuery = "SELECT * FROM firstdatabase";
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery,null);

        if(cursor.moveToFirst()){
            do{
                Product product = new Product();
                product.setId(Integer.parseInt(cursor.getString(0)));
                product.setIsbn(cursor.getString(1));
                product.setIngredients(cursor.getString(2));
                productList.add(product);
            }while (cursor.moveToNext());
        }
        return productList;

    }

Java文件：

public class BarCodeActivity extends AppCompatActivity {

    MySQLiteHelper db1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_bar_code);
        db1 = new MySQLiteHelper(this);
        Log.d("Insert", "Inserting data...");
        db1.addIngredientsToTable(new Product(1, "89470001033", "Lowfat yogurt, mango, milk, water"));

        Log.d("Reading: ", "Reading all products");
        ArrayList<Product> products = db1.getAllProducts();

        for(Product product : products){
            String log = "Id: " + product.getId() + ", ISBN: " + product.getIsbn() + ", Ingredients: " + product.getIngredients();
            Log.d("Product:", log);
        }

Answer 1

您的CREATE_PROTOTYPE_TABLE字符串不正确，分号丢失（;）：

使用以下内容：

String CREATE_PROTOTYPE_TABLE = "CREATE TABLE " + TABLE_NAME + "("
                + KEY_ID + " INTEGER PRIMARY KEY autoincrement," + KEY_ISBN + " TEXT,"
                + KEY_INGREDIENTS + " TEXT" + ");";

SQLIte没有创建数据库表

1 个答案: