Общая стоимость с использованием rawQuery в android

Question

Я пытался получить стоимость из базы данных и попытаться сделать общую сумму. Я использовал rawQuery, но всегда crashed.I думаю Theres проблемы в моей rawQuery..i сих пор не могу получить общее после много раз я пробовал ..

это код:

DBAdapter

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.util.Log; 


// ------------------------------------ DBAdapter.java --------------------------------------------- 
// TO USE: 
// Change the package (at top) to match your project. 
// Search for "TODO", and make the appropriate changes. 
public class DBAdapter { 

    ///////////////////////////////////////////////////////////////////// 
    // Constants & Data 
    ///////////////////////////////////////////////////////////////////// 
    // For logging: 
    private static final String TAG = "DBAdapter"; 

    // DB Fields 
    public static final String KEY_ROWID = "_id"; 
    public static final int COL_ROWID = 0; 
    /* 
    * CHANGE 1: 
    */ 
    // TODO: Setup your fields here: 
    public static final String KEY_NAME = "name"; 
    public static final String KEY_QUANTITY = "studentnum"; 
    public static final String KEY_PRICE = "favcolour"; 

    // TODO: Setup your field numbers here (0 = KEY_ROWID, 1=...) 
    public static final int COL_NAME = 1; 
    public static final int COL_QUANTITY = 2; 
    public static final int COL_PRICE = 3; 


    public static final String[] ALL_KEYS = new String[] {KEY_ROWID, KEY_NAME, KEY_QUANTITY, KEY_PRICE}; 

    // DB info: it's name, and the table we are using (just one). 
    public static final String DATABASE_NAME = "MyDb"; 
    public static final String DATABASE_TABLE = "mainTable"; 
    // Track DB version if a new version of your app changes the format. 
    public static final int DATABASE_VERSION = 2; 

    private static final String DATABASE_CREATE_SQL = 
      "create table " + DATABASE_TABLE 
        + " (" + KEY_ROWID + " integer primary key autoincrement, " 

      /* 
      * CHANGE 2: 
      */ 
        // TODO: Place your fields here! 
        // + KEY_{...} + " {type} not null" 
        // - Key is the column name you created above. 
        // - {type} is one of: text, integer, real, blob 
        //  (http://www.sqlite.org/datatype3.html) 
        // - "not null" means it is a required field (must be given a value). 
        // NOTE: All must be comma separated (end of line!) Last one must have NO comma!! 
        + KEY_NAME + " text not null, " 
        + KEY_QUANTITY + " integer not null, " 
        + KEY_PRICE + " string not null" 

        // Rest of creation: 
        + ");"; 

    // Context of application who uses us. 
    private final Context context; 

    private DatabaseHelper myDBHelper; 
    private SQLiteDatabase db; 

    ///////////////////////////////////////////////////////////////////// 
    // Public methods: 
    ///////////////////////////////////////////////////////////////////// 

    public DBAdapter(Context ctx) { 
     this.context = ctx; 
     myDBHelper = new DatabaseHelper(context); 
    } 

    // Open the database connection. 
    public DBAdapter open() { 
     db = myDBHelper.getWritableDatabase(); 
     return this; 
    } 

    // Close the database connection. 
    public void close() { 
     myDBHelper.close(); 
    } 

    // Add a new set of values to the database. 
    public long insertRow(String name, String studentNum, String favColour) { 
     /* 
     * CHANGE 3: 
     */ 
     // TODO: Update data in the row with new fields. 
     // TODO: Also change the function's arguments to be what you need! 
     // Create row's data: 
     ContentValues initialValues = new ContentValues(); 
     initialValues.put(KEY_NAME, name); 
     initialValues.put(KEY_QUANTITY, studentNum); 
     initialValues.put(KEY_PRICE, favColour); 

     // Insert it into the database. 
     return db.insert(DATABASE_TABLE, null, initialValues); 
    } 

    // Delete a row from the database, by rowId (primary key) 
    public boolean deleteRow(long rowId) { 
     String where = KEY_ROWID + "=" + rowId; 
     return db.delete(DATABASE_TABLE, where, null) != 0; 
    } 

    public Cursor getTotalPrice() { 
     Cursor c = db.rawQuery("SELECT SUM("+ KEY_PRICE +")from " + DATABASE_TABLE, null); 
     return c; 
     } 


    public void deleteAll() { 
     Cursor c = getAllRows(); 
     long rowId = c.getColumnIndexOrThrow(KEY_ROWID); 
     if (c.moveToFirst()) { 
      do { 
       deleteRow(c.getLong((int) rowId)); 
      } while (c.moveToNext()); 
     } 
     c.close(); 
    } 

    // Return all data in the database. 
    public Cursor getAllRows() { 
     String where = null; 
     Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS, 
       where, null, null, null, null, null); 
     if (c != null) { 
      c.moveToFirst(); 
     } 
     return c; 
    } 

    // Get a specific row (by rowId) 
    public Cursor getRow(long rowId) { 
     String where = KEY_ROWID + "=" + rowId; 
     Cursor c = db.query(true, DATABASE_TABLE, ALL_KEYS, 
       where, null, null, null, null, null); 
     if (c != null) { 
      c.moveToFirst(); 
     } 
     return c; 
    } 

    // Change an existing row to be equal to new data. 
    public boolean updateRow(long rowId, String name, int studentNum, String favColour) { 
     String where = KEY_ROWID + "=" + rowId; 

     /* 
     * CHANGE 4: 
     */ 
     // TODO: Update data in the row with new fields. 
     // TODO: Also change the function's arguments to be what you need! 
     // Create row's data: 
     ContentValues newValues = new ContentValues(); 
     newValues.put(KEY_NAME, name); 
     newValues.put(KEY_QUANTITY, studentNum); 
     newValues.put(KEY_PRICE, favColour); 

     // Insert it into the database. 
     return db.update(DATABASE_TABLE, newValues, where, null) != 0; 
    } 




    ///////////////////////////////////////////////////////////////////// 
    // Private Helper Classes: 
    ///////////////////////////////////////////////////////////////////// 

    /** 
    * Private class which handles database creation and upgrading. 
    * Used to handle low-level database access. 
    */ 
    private static class DatabaseHelper extends SQLiteOpenHelper 
    { 
     DatabaseHelper(Context context) { 
      super(context, DATABASE_NAME, null, DATABASE_VERSION); 
     } 

     @Override 
     public void onCreate(SQLiteDatabase _db) { 
      _db.execSQL(DATABASE_CREATE_SQL); 
     } 

     @Override 
     public void onUpgrade(SQLiteDatabase _db, int oldVersion, int newVersion) { 
      Log.w(TAG, "Upgrading application's database from version " + oldVersion 
        + " to " + newVersion + ", which will destroy all old data!"); 

      // Destroy old database: 
      _db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE); 

      // Recreate new database: 
      onCreate(_db); 
     } 
    } 
} 

ListPrice:

import android.app.AlertDialog; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.database.Cursor; 
import android.database.sqlite.SQLiteDatabase; 
import android.support.v7.app.ActionBarActivity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.*; 


/** 
* Created by User on 6/2/2015. 
*/ 

public class Listprice extends ActionBarActivity { 

    DBAdapter myDb; 

    @Override 

    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.listprice); 

     openDB(); 
     TextView textView = (TextView) findViewById(R.id.order90); 
     TextView textView1 = (TextView) findViewById(R.id.quan90); 
     TextView textView2 = (TextView) findViewById(R.id.price90); 
     TextView textView3 = (TextView) findViewById(R.id.totalprice); 

     Bundle extras = getIntent().getExtras(); 


     if (extras != null) { 
      String newText = extras.getString("firstmessage"); 
      String newText1 = extras.getString("secondmessage"); 
      String newText2 = extras.getString("thirdmessage"); 

      if (newText != null) { 
       textView.setText(newText); 
      } 
      if (newText1 != null) { 
       textView1.setText(newText1); 
      } 
      if (newText2 != null) { 
       textView2.setText(newText2); 
      } 
     } 
     String num1 = textView.getText().toString().trim(); 
     int num2 = Integer.parseInt(textView1.getText().toString()); 
     int num3 = Integer.parseInt(textView2.getText().toString()); 

     int num4 = num2 * num3; 

     registerListClickCallBack(); 
     myDb.insertRow(num1, "Quantity = " + num2, ""+num4); 
     populateListViewFromDB(); 

     Cursor sum=myDb.getTotalPrice(); 
     textView3.setText(""+sum); 

    } 


    private void populateListViewFromDB() { 


     Cursor cursor = myDb.getAllRows(); 
     //Query for the record we just added. 
     //Use the ID: 
     startManagingCursor(cursor); 

     String[] fromFieldNames = new String[] 
       {DBAdapter.KEY_NAME, DBAdapter.KEY_QUANTITY, DBAdapter.KEY_PRICE}; 

     int[] toViewIDs = new int[] 
       {R.id.item_name, R.id.quantities, R.id.pricest}; 

     SimpleCursorAdapter myCursorAdapter = 
       new SimpleCursorAdapter(
         this, 
         R.layout.item_layout, 
         cursor, 
         fromFieldNames, 
         toViewIDs 
       ); 

     // Set the adapter for the list view 
     ListView myList = (ListView) findViewById(R.id.listViewFromDB); 
     myList.setAdapter(myCursorAdapter); 

    } 

    private void openDB(){ 

     myDb = new DBAdapter(this); 
     myDb.open(); 
    } 

    @Override 
    protected void onDestroy() { 
     super.onDestroy(); 
     closeDB(); 
    } 



    private void closeDB() { 
     myDb.close(); 
    } 


    private void registerListClickCallBack() { 

     ListView myList = (ListView) findViewById(R.id.listViewFromDB); 
     myList.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> parent, View viewClicked, 
            int position, long idInDB) { 

       updateItemForId(idInDB); 

      } 
     }); 
    } 


    private void updateItemForId(final long idInDB) { 

     final Cursor cursor = myDb.getRow(idInDB); 
     if (cursor.moveToFirst()) { 
      AlertDialog.Builder alertDialog = new AlertDialog.Builder(Listprice.this); 

      // Setting Dialog Title 
      alertDialog.setTitle("Confirm Delete..."); 

      // Setting Dialog Message 
      alertDialog.setMessage("Are you sure you want delete this?"); 


      // Setting Positive "Yes" Button 
      alertDialog.setPositiveButton("YES", new DialogInterface.OnClickListener() { 
       public void onClick(DialogInterface dialog,int which) { 

        // Write your code here to invoke YES event 
        Toast.makeText(getApplicationContext(), "You clicked on YES", Toast.LENGTH_SHORT).show(); 
        myDb.deleteRow(idInDB); 
        populateListViewFromDB(); 
       } 
      }); 

      // Setting Negative "NO" Button 
      alertDialog.setNegativeButton("NO", new DialogInterface.OnClickListener() { 
       public void onClick(DialogInterface dialog, int which) { 
        // Write your code here to invoke NO event 
        Toast.makeText(getApplicationContext(), "You clicked on NO", Toast.LENGTH_SHORT).show(); 
        dialog.cancel(); 
       } 
      }); 

      // Showing Alert Message 
      alertDialog.show(); 
     } 
     cursor.close(); 
     populateListViewFromDB(); 
    } 

    public void clear(View view) { 
     myDb.deleteAll(); 
     populateListViewFromDB(); 
    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 


    public void addFood(View view) { 
     Intent gotofood = new Intent(this, food.class); 
     startActivity(gotofood); 
    } 

    public void addDrinks(View view) { 
     Intent gotodrinks = new Intent(this, drink.class); 
     startActivity(gotodrinks); 
    } 

    public void gotomainmaenu(View view) { 
     Intent gotomain = new Intent(this, MainActivity.class); 
     startActivity(gotomain); 
    } 


} 

Answer 1

Это звучит, как вы хотите, сумма стоимости каждого элемента, умноженной на количество этого элемента. Если это так, это должно сработать:

public double getTotalPrice() { 
    String sql = "select sum(" + KEY_QUANTITY + " * " + KEY_PRICE + ") from " 
      + DATABASE_TABLE; 
    Cursor cursor = db.rawQuery(sql, null); 
    if (cursor.moveToFirst()) { 
     return cursor.getDouble(0); 
    } 
    return 0; 
}