usar - Crear base de datos SQLite en android

usar nuestra propia base de datos sqlite en android

Question

Quiero crear una base de datos SQLite en mi aplicación, que contiene tres tablas, agregaré datos en tablas y los usaré más adelante.

pero me gusta mantener la base de datos, como si la primera vez que se instala la aplicación comprueba si la base de datos existe o no, si existe la actualiza de lo contrario, si no, crea una nueva base de datos.

Además, estoy haciendo una clase de base de datos para facilitar mi aplicación, por lo que no crearé una actividad para la creación de mi base de datos.

si hay posibles consejos, por favor comparte conmigo

Answer 1

¿Por qué no consultar la documentation o el código de muestra que se envía con el SDK? Hay código en los ejemplos sobre cómo crear / actualizar / llenar / leer bases de datos usando la clase auxiliar que se describe en el documento que he vinculado.

Answer 2

Aquí está el código

DatabaseMyHandler.class

public class DatabaseMyHandler extends SQLiteOpenHelper {

    private SQLiteDatabase myDataBase;
    private Context context = null;
    private static String TABLE_NAME = "customer";
    public static final String DATABASE_NAME = "Student.db";
    public final static String DATABASE_PATH = "/data/data/com.pkgname/databases/";
    public static final int DATABASE_VERSION = 2;

    public DatabaseMyHandler(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        this.context = context;
        try {
            createDatabase();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        myDataBase = sqLiteDatabase;

    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }

    //Check database already exists or not

    private boolean checkDatabaseExists() {
        boolean checkDB = false;
        try {
            String PATH = DATABASE_PATH + DATABASE_NAME;
            File dbFile = new File(PATH);
            checkDB = dbFile.exists();

        } catch (SQLiteException e) {

        }
        return checkDB;
    }


    //Create a empty database on the system
    public void createDatabase() throws IOException {
        boolean dbExist = checkDatabaseExists();

        if (dbExist) {
            Log.v("DB Exists", "db exists");
        }

        boolean dbExist1 = checkDatabaseExists();
        if (!dbExist1) {
            this.getWritableDatabase();
            try {
                this.close();
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }
    }

    //Copies your database from your local assets-folder to the just created empty database in the system folder
    private void copyDataBase() throws IOException {
        String outFileName = DATABASE_PATH + DATABASE_NAME;
        OutputStream myOutput = new FileOutputStream(outFileName);
        InputStream myInput = context.getAssets().open(DATABASE_NAME);

        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
        myInput.close();
        myOutput.flush();
        myOutput.close();
    }


    //Open Database
    public void openDatabase() throws SQLException {
        String PATH = DATABASE_PATH + DATABASE_NAME;
        myDataBase = SQLiteDatabase.openDatabase(PATH, null, SQLiteDatabase.OPEN_READWRITE);
    }

    //for insert data into database


    public void insertCustomer(String customer_id, String email_id, String password, String description, int balance_amount) {
        try {
            openDatabase();
            SQLiteDatabase db = this.getWritableDatabase();
            ContentValues contentValues = new ContentValues();
            contentValues.put("customer_id", customer_id);
            contentValues.put("email_id", email_id);
            contentValues.put("password", password);
            contentValues.put("description", description);
            contentValues.put("balance_amount", balance_amount);
            db.insert(TABLE_NAME, null, contentValues);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }


    public ArrayList<ModelCreateCustomer> getLoginIdDetail(String email_id, String password) {

        ArrayList<ModelCreateCustomer> result = new ArrayList<ModelCreateCustomer>();
        //boolean flag = false;
        String selectQuery = "SELECT * FROM " + TABLE_NAME + " WHERE email_id=''" + email_id + "'' AND password=''" + password + "''";

        try {
            openDatabase();
            Cursor cursor = myDataBase.rawQuery(selectQuery, null);
            //cursor.moveToFirst();


            if (cursor.getCount() > 0) {
                if (cursor.moveToFirst()) {
                    do {
                        ModelCreateCustomer model = new ModelCreateCustomer();
                        model.setId(cursor.getInt(cursor.getColumnIndex("id")));
                        model.setCustomerId(cursor.getString(cursor.getColumnIndex("customer_id")));
                        model.setCustomerEmailId(cursor.getString(cursor.getColumnIndex("email_id")));
                        model.setCustomerPassword(cursor.getString(cursor.getColumnIndex("password")));
                        model.setCustomerDesription(cursor.getString(cursor.getColumnIndex("description")));
                        model.setCustomerBalanceAmount(cursor.getInt(cursor.getColumnIndex("balance_amount")));

                        result.add(model);
                    }
                    while (cursor.moveToNext());
                }
                Toast.makeText(context, "Login Successfully", Toast.LENGTH_SHORT).show();
            }

//            Log.e("Count", "" + cursor.getCount());
            cursor.close();
            myDataBase.close();
        } catch (SQLException e) {
            e.printStackTrace();
        }


        return result;
    }

    public void updateCustomer(String id, String email_id, String description, int balance_amount) {

        try {
            openDatabase();
            SQLiteDatabase db = this.getWritableDatabase();
            ContentValues contentValues = new ContentValues();
            contentValues.put("email_id", email_id);
            contentValues.put("description", description);
            contentValues.put("balance_amount", balance_amount);

            db.update(TABLE_NAME, contentValues, "id=" + id, null);

        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

Customer.class

public class Customer extends AppCompatActivity{
  private DatabaseMyHandler mydb;
  @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_customer);

        mydb = new DatabaseMyHandler(CreateCustomerActivity.this);
 mydb.insertCustomer("1", "[email protected]", "123", "test", 100);

    }

}

Answer 3

Mejor ejemplo es [aquí]

 try {
   myDB = this.openOrCreateDatabase("DatabaseName", MODE_PRIVATE, null);

   /* Create a Table in the Database. */
   myDB.execSQL("CREATE TABLE IF NOT EXISTS "
     + TableName
     + " (Field1 VARCHAR, Field2 INT(3));");

   /* Insert data to a Table*/
   myDB.execSQL("INSERT INTO "
     + TableName
     + " (Field1, Field2)"
     + " VALUES (''Saranga'', 22);");

   /*retrieve data from database */
   Cursor c = myDB.rawQuery("SELECT * FROM " + TableName , null);

   int Column1 = c.getColumnIndex("Field1");
   int Column2 = c.getColumnIndex("Field2");

   // Check if our result was valid.
   c.moveToFirst();
   if (c != null) {
    // Loop through all Results
    do {
     String Name = c.getString(Column1);
     int Age = c.getInt(Column2);
     Data =Data +Name+"/"+Age+"/n";
    }while(c.moveToNext());
   }

Answer 4

Para comprender cómo usar la base de datos sqlite en Android con las mejores prácticas, vea - Android con la base de datos sqlite

Hay pocas clases sobre las que debe saber y que le ayudarán a modelar sus tablas y modelos, es decir, android.provider.BaseColumns

A continuación se muestra un ejemplo de una tabla

public class ProductTable implements BaseColumns {
  public static final String NAME = "name";
  public static final String PRICE = "price";
  public static final String TABLE_NAME = "products";

  public static final String CREATE_QUERY = "create table " + TABLE_NAME + " (" +
      _ID + " INTEGER, " +
      NAME + " TEXT, " +
      PRICE + " INTEGER)";

  public static final String DROP_QUERY = "drop table " + TABLE_NAME;
  public static final String SElECT_QUERY = "select * from " + TABLE_NAME;
}

Answer 5

Si desea mantener la base de datos entre las desinstalaciones, debe colocarla en la tarjeta SD. Este es el único lugar que no se eliminará en el momento en que se elimine tu aplicación. Pero a cambio, el usuario puede borrarlo todo el tiempo.

Si coloca su base de datos en la tarjeta SD ya no puede usar SQLiteOpenHelper , pero puede usar la fuente y la arquitectura de esta clase para obtener algunas ideas sobre cómo implementar la creación, actualización y apertura de un databse.

Answer 6

Un simple ejemplo de base de datos para insertar la Lista de todos los días de la vida del día en DB y obtener una lista de todas las listas de tareas pendientes.

public class MyDatabaseHelper extends SQLiteOpenHelper {

// Logcat tag
private static final String LOG = "DatabaseHelper";

// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "SQLiteDemoDB";

// Table Names
private static final String TABLE_TODO = "todos";

// column names
private static final String KEY_ID = "id";
private static final String KEY_CREATED_AT = "created_at";
private static final String KEY_TODO = "todoDescr";

// *********************************************************************************************
public MyDatabaseHelper(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {

    db.execSQL(CREATE_TABLE_TODO);


}

// Upgrading database **************************************************************************
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_TODO);


    // Create tables again
    onCreate(db);
}

// Creating Table TABLE_TEAM
String CREATE_TABLE_TODO = "CREATE TABLE " + TABLE_TODO + "("
        + KEY_ID + " integer primary key autoincrement, "
        + KEY_TODO + " text, "
        + KEY_CREATED_AT + " text" + ")";


// insert values of todo
public boolean InsertTodoDetails(String todo, String createdAt) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();
    contentValues.put(KEY_TODO, todo);
    contentValues.put(KEY_CREATED_AT, createdAt);


    long rowInserted = db.insert(TABLE_TODO, null, contentValues);
    db.close();
    return true;
}


// Select values of todo
public Cursor GetAllTodoDetails() {
    SQLiteDatabase db = this.getReadableDatabase();


    String query = "SELECT * FROM " + TABLE_TODO;
    Cursor mcursor = db.rawQuery(query, null);

    if (mcursor != null) {
        mcursor.moveToFirst();
    }

    return mcursor;

}



}

Mi actividad Para guardar y obtener el registro.

public class MyDbActivity extends AppCompatActivity {

    @Bind(R.id.edt_todo)
    EditText edtTodo;
    @Bind(R.id.btn_save)
    Button btnSave;

    MyDatabaseHelper db;
    @Bind(R.id.btn_getTodo)
    Button btnGetTodo;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_db);
        ButterKnife.bind(this);

// creating database object
        db = new MyDatabaseHelper(this);


    }

    @OnClick(R.id.btn_save)
    public void onViewClicked() {


        String datetime = "";
        try {
            SimpleDateFormat dateformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            datetime = dateformat.format(new Date());
        } catch (Exception e) {
            e.printStackTrace();
        }

        db.InsertTodoDetails(edtTodo.getText().toString().trim(), datetime);

    }

    @OnClick(R.id.btn_getTodo)
    public void onGetTodoClicked() {
        String todos = "";
        Cursor TodoList = db.GetAllTodoDetails();
        if (TodoList.moveToFirst()) {
            do {
                if (todos.equals("")) {
                    todos = TodoList.getString(TodoList.getColumnIndex("todoDescr"));

                } else {
                    todos = todos + ", " + TodoList.getString(TodoList.getColumnIndex("todoDescr"));
                }
                // do what ever you want here
            } while (TodoList.moveToNext());
        }
        TodoList.close();
        Toast.makeText(this, "" + todos, Toast.LENGTH_SHORT).show();

    }
}

Answer 7

este es el código fuente completo para uso directo,

    public class CardDBDAO {

        protected SQLiteDatabase database;
        private DataBaseHelper dbHelper;
        private Context mContext;

        public CardDBDAO(Context context) {
            this.mContext = context;
            dbHelper = DataBaseHelper.getHelper(mContext);
            open();

        }

        public void open() throws SQLException {
            if(dbHelper == null)
                dbHelper = DataBaseHelper.getHelper(mContext);
            database = dbHelper.getWritableDatabase();
        }

    }



    public class DataBaseHelper extends SQLiteOpenHelper {

        private static final String DATABASE_NAME = "mydbnamedb";
        private static final int DATABASE_VERSION = 1;

        public static final String CARDS_TABLE = "tbl_cards";
        public static final String POICATEGORIES_TABLE = "tbl_poicategories";
        public static final String POILANGS_TABLE = "tbl_poilangs";

        public static final String ID_COLUMN = "id";

        public static final String POI_ID = "poi_id";
        public static final String POICATEGORIES_COLUMN = "poi_categories";

        public static final String POILANGS_COLUMN = "poi_langs";

        public static final String CARDS = "cards";
        public static final String CARD_ID = "card_id";
        public static final String CARDS_PCAT_ID = "pcat_id";

        public static final String CREATE_PLANG_TABLE = "CREATE TABLE "
                + POILANGS_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY,"
                + POILANGS_COLUMN + " TEXT, " + POI_ID + " TEXT)";

        public static final String CREATE_PCAT_TABLE = "CREATE TABLE "
                + POICATEGORIES_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY,"
                + POICATEGORIES_COLUMN + " TEXT, " + POI_ID + " TEXT)";

        public static final String CREATE_CARDS_TABLE = "CREATE TABLE "
                + CARDS_TABLE + "(" + ID_COLUMN + " INTEGER PRIMARY KEY," + CARD_ID
                + " TEXT, " + CARDS_PCAT_ID + " TEXT, " + CARDS + " TEXT)";

        private static DataBaseHelper instance;

        public static synchronized DataBaseHelper getHelper(Context context) {
            if (instance == null)
                instance = new DataBaseHelper(context);
            return instance;
        }

        private DataBaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onOpen(SQLiteDatabase db) {
            super.onOpen(db);
            if (!db.isReadOnly()) {
                // Enable foreign key constraints
                // db.execSQL("PRAGMA foreign_keys=ON;");
            }
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL(CREATE_PCAT_TABLE);
            db.execSQL(CREATE_PLANG_TABLE);
            db.execSQL(CREATE_CARDS_TABLE);
        }

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

        }
    }




    public class PoiLangDAO extends CardDBDAO {

            private static final String WHERE_ID_EQUALS = DataBaseHelper.ID_COLUMN
                    + " =?";

            public PoiLangDAO(Context context) {
                super(context);
            }

            public long save(PLang plang_data) {

                ContentValues values = new ContentValues();
                values.put(DataBaseHelper.POI_ID, plang_data.getPoi_id());
                values.put(DataBaseHelper.POILANGS_COLUMN, plang_data.getLangarr());

                return database
                        .insert(DataBaseHelper.POILANGS_TABLE, null, values);
            }

            public long update(PLang plang_data) {
                ContentValues values = new ContentValues();
                values.put(DataBaseHelper.POI_ID, plang_data.getPoi_id());
                values.put(DataBaseHelper.POILANGS_COLUMN, plang_data.getLangarr());

                long result = database.update(DataBaseHelper.POILANGS_TABLE,
                        values, WHERE_ID_EQUALS,
                        new String[] { String.valueOf(plang_data.getId()) });
                Log.d("Update Result:", "=" + result);
                return result;

            }

            public int deleteDept(PLang plang_data) {
                return database.delete(DataBaseHelper.POILANGS_TABLE,
                        WHERE_ID_EQUALS, new String[] { plang_data.getId() + "" });
            }

            public List<PLang> getPLangs1() {
                List<PLang> plang_list = new ArrayList<PLang>();
                Cursor cursor = database.query(DataBaseHelper.POILANGS_TABLE,
                        new String[] { DataBaseHelper.ID_COLUMN, DataBaseHelper.POI_ID,
                                DataBaseHelper.POILANGS_COLUMN }, null, null, null,
                        null, null);

                while (cursor.moveToNext()) {
                    PLang plang_bin = new PLang();
                    plang_bin.setId(cursor.getInt(0));
                    plang_bin.setPoi_id(cursor.getString(1));
                    plang_bin.setLangarr(cursor.getString(2));
                    plang_list.add(plang_bin);
                }
                return plang_list;
            }

            public List<PLang> getPLangs(String pid) {
                List<PLang> plang_list = new ArrayList<PLang>();

                String selection = DataBaseHelper.POI_ID + "=?";
                String[] selectionArgs = { pid };

                Cursor cursor = database.query(DataBaseHelper.POILANGS_TABLE,
                        new String[] { DataBaseHelper.ID_COLUMN, DataBaseHelper.POI_ID,
                                DataBaseHelper.POILANGS_COLUMN }, selection,
                        selectionArgs, null, null, null);

                while (cursor.moveToNext()) {
                    PLang plang_bin = new PLang();
                    plang_bin.setId(cursor.getInt(0));
                    plang_bin.setPoi_id(cursor.getString(1));
                    plang_bin.setLangarr(cursor.getString(2));
                    plang_list.add(plang_bin);
                }
                return plang_list;
            }

            public void loadPLangs(String poi_id, String langarrs) {
                PLang plangbin = new PLang(poi_id, langarrs);

                List<PLang> plang_arr = new ArrayList<PLang>();
                plang_arr.add(plangbin);

                for (PLang dept : plang_arr) {
                    ContentValues values = new ContentValues();
                    values.put(DataBaseHelper.POI_ID, dept.getPoi_id());
                    values.put(DataBaseHelper.POILANGS_COLUMN, dept.getLangarr());
                    database.insert(DataBaseHelper.POILANGS_TABLE, null, values);
                }
            }

        }




        public class PLang {

            public PLang() {
                super();
            }

            public PLang(String poi_id, String langarrs) {
                // TODO Auto-generated constructor stub

                this.poi_id = poi_id;
                this.langarr = langarrs;
            }

            public int getId() {
                return id;
            }

            public void setId(int id) {
                this.id = id;
            }

            public String getPoi_id() {
                return poi_id;
            }

            public void setPoi_id(String poi_id) {
                this.poi_id = poi_id;
            }

            public String getLangarr() {
                return langarr;
            }

            public void setLangarr(String langarr) {
                this.langarr = langarr;
            }

            private int id;
            private String poi_id;
            private String langarr;

    }

Answer 8

    public class MyDatabaseHelper extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "MyDb.db";

    private static final int DATABASE_VERSION = 1;

    // Database creation sql statement
    private static final String DATABASE_CREATE_FRIDGE_ITEM = "create table FridgeItem(id integer primary key autoincrement,f_id text not null,food_item text not null,quantity text not null,measurement text not null,expiration_date text not null,current_date text not null,flag text not null,location text not null);";

    public MyDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    // Method is called during creation of the database
    @Override
    public void onCreate(SQLiteDatabase database) {
        database.execSQL(DATABASE_CREATE_FRIDGE_ITEM);
    }

    // Method is called during an upgrade of the database,
    @Override
    public void onUpgrade(SQLiteDatabase database,int oldVersion,int newVersion){
        Log.w(MyDatabaseHelper.class.getName(),"Upgrading database from version " + oldVersion + " to "
                         + newVersion + ", which will destroy all old data");
        database.execSQL("DROP TABLE IF EXISTS FridgeItem");
        onCreate(database);
    }
}



    public class CommentsDataSource {

    private MyDatabaseHelper dbHelper;

    private SQLiteDatabase database;

    public String stringArray[];

    public final static String FOOD_TABLE = "FridgeItem"; // name of table
    public final static String FOOD_ITEMS_DETAILS = "FoodDetails"; // name of table

    public final static String P_ID = "id"; // pid
    public final static String FOOD_ID = "f_id"; // id value for food item
    public final static String FOOD_NAME = "food_item"; // name of food
    public final static String FOOD_QUANTITY = "quantity"; // quantity of food item
    public final static String FOOD_MEASUREMENT = "measurement"; // measurement of food item
    public final static String FOOD_EXPIRATION = "expiration_date"; // expiration date of food item
    public final static String FOOD_CURRENTDATE = "current_date"; //  date of food item added
    public final static String FLAG = "flag"; 
    public final static String LOCATION = "location";
    /**
     * 
     * @param context
     */
    public CommentsDataSource(Context context) {
        dbHelper = new MyDatabaseHelper(context);
        database = dbHelper.getWritableDatabase();
    }

    public long insertFoodItem(String id, String name,String quantity, String measurement, String currrentDate,String expiration,String flag,String location) {
        ContentValues values = new ContentValues();
        values.put(FOOD_ID, id);
        values.put(FOOD_NAME, name);
        values.put(FOOD_QUANTITY, quantity);
        values.put(FOOD_MEASUREMENT, measurement);
        values.put(FOOD_CURRENTDATE, currrentDate);
        values.put(FOOD_EXPIRATION, expiration);
        values.put(FLAG, flag);
        values.put(LOCATION, location);
        return database.insert(FOOD_TABLE, null, values);
    }

    public long insertFoodItemsDetails(String id, String name,String quantity, String measurement, String currrentDate,String expiration) {
        ContentValues values = new ContentValues();
        values.put(FOOD_ID, id);
        values.put(FOOD_NAME, name);
        values.put(FOOD_QUANTITY, quantity);
        values.put(FOOD_MEASUREMENT, measurement);
        values.put(FOOD_CURRENTDATE, currrentDate);
        values.put(FOOD_EXPIRATION, expiration);
        return database.insert(FOOD_ITEMS_DETAILS, null, values);

    }

    public Cursor selectRecords(String id) {
        String[] cols = new String[] { FOOD_ID, FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION,FLAG,LOCATION,P_ID};
        Cursor mCursor = database.query(true, FOOD_TABLE, cols, P_ID+"=?", new String[]{id}, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor; // iterate to get each value.
    }

    public Cursor selectAllName() {
        String[] cols = new String[] { FOOD_NAME};
        Cursor mCursor = database.query(true, FOOD_TABLE, cols, null, null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor; // iterate to get each value.
    }

    public Cursor selectAllRecords(String loc) {
        String[] cols = new String[] { FOOD_ID, FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION,FLAG,LOCATION,P_ID};
        Cursor mCursor = database.query(true, FOOD_TABLE, cols, LOCATION+"=?", new String[]{loc}, null, null, null, null);
        int size=mCursor.getCount();
        stringArray = new String[size];
        int i=0;
        if (mCursor != null) {
            mCursor.moveToFirst();
            FoodInfo.arrayList.clear();
                while (!mCursor.isAfterLast()) {
                    String name=mCursor.getString(1);
                    stringArray[i]=name;
                    String quant=mCursor.getString(2);
                    String measure=mCursor.getString(3);
                    String expir=mCursor.getString(4);
                    String id=mCursor.getString(7);
                    FoodInfo fooditem=new FoodInfo();
                    fooditem.setName(name);
                    fooditem.setQuantity(quant);
                    fooditem.setMesure(measure);
                    fooditem.setExpirationDate(expir);
                    fooditem.setid(id);
                    FoodInfo.arrayList.add(fooditem);
                    mCursor.moveToNext();
                    i++;
                }
        }
        return mCursor; // iterate to get each value.
    }

    public Cursor selectExpDate() {
        String[] cols = new String[] {FOOD_NAME, FOOD_QUANTITY, FOOD_MEASUREMENT, FOOD_EXPIRATION};
        Cursor mCursor = database.query(true, FOOD_TABLE, cols, null, null, null, null,  FOOD_EXPIRATION, null);
        int size=mCursor.getCount();
        stringArray = new String[size];
        if (mCursor != null) {
            mCursor.moveToFirst();
            FoodInfo.arrayList.clear();
                while (!mCursor.isAfterLast()) {
                    String name=mCursor.getString(0);
                    String quant=mCursor.getString(1);
                    String measure=mCursor.getString(2);
                    String expir=mCursor.getString(3);
                    FoodInfo fooditem=new FoodInfo();
                    fooditem.setName(name);
                    fooditem.setQuantity(quant);
                    fooditem.setMesure(measure);
                    fooditem.setExpirationDate(expir);
                    FoodInfo.arrayList.add(fooditem);
                    mCursor.moveToNext();
                }
        }
        return mCursor; // iterate to get each value.
    }

    public int UpdateFoodItem(String id, String quantity, String expiration){
       ContentValues values=new ContentValues();
       values.put(FOOD_QUANTITY, quantity);
       values.put(FOOD_EXPIRATION, expiration);
       return database.update(FOOD_TABLE, values, P_ID+"=?", new String[]{id});   
      }

    public void deleteComment(String id) {
        System.out.println("Comment deleted with id: " + id);
        database.delete(FOOD_TABLE, P_ID+"=?", new String[]{id});
        }

}