從數據庫中獲取和刪除行[android]

Question

我想從數據庫中獲取一行並將其顯示在MyActivity類中。但是我想按排的位置來做。與刪除相同的問題。如果我點擊列表項目，我想刪除那個位置（簡單的行）。

public class MyActivity extends Activity { 
public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     DatabaseHandler db = new DatabaseHandler(this); 

     /** 
     * CRUD Operations 
     * */ 
     // Inserting Contacts 
     Log.d("Insert: ", "Inserting .."); 
     db.addContact(new Contact("Ravi", "9100000000")); 
     db.addContact(new Contact("Srinivas", "9199999999")); 
     db.addContact(new Contact("Tommy", "9522222222")); 
     db.addContact(new Contact("Karthik", "9533333333")); 

     List<Contact> contacts = db.getAllContacts(); 

     // here i want to get a simple contact by its position in table. 
     // here i want to delete a simple contact by its position in table. 

}

這是我的數據庫處理器：

public class DatabaseHandler extends SQLiteOpenHelper { 

    private static final int DATABASE_VERSION = 1; 
    private static final String DATABASE_NAME = "contactsManager"; 
    private static final String TABLE_CONTACTS = "contacts"; 
    private static final String KEY_ID = "id"; 
    private static final String KEY_NAME = "name"; 
    private static final String KEY_PH_NO = "phone_number"; 

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

    // Adding new contact 
    void addContact(Contact contact) { 
     SQLiteDatabase db = this.getWritableDatabase(); 

     ContentValues values = new ContentValues(); 
     values.put(KEY_NAME, contact.getName()); // Contact Name 
     values.put(KEY_PH_NO, contact.getPhoneNumber()); // Contact Phone 

     // Inserting Row 
     db.insert(TABLE_CONTACTS, null, values); 
     db.close(); // Closing database connection 
    } 

    // Getting single contact 
    Contact getContact(int id) { 
     SQLiteDatabase db = this.getReadableDatabase(); 

     Cursor cursor = db.query(TABLE_CONTACTS, new String[] { KEY_ID, 
       KEY_NAME, KEY_PH_NO }, KEY_ID + "=?", 
       new String[] { String.valueOf(id) }, null, null, null, null); 
     if (cursor != null) 
      cursor.moveToFirst(); 

     Contact contact = new Contact(Integer.parseInt(cursor.getString(0)), 
       cursor.getString(1), cursor.getString(2)); 
     // return contact 
     return contact; 
    }  

    // Deleting single contact 
    public void deleteContact(Contact contact) { 
     SQLiteDatabase db = this.getWritableDatabase(); 
     db.delete(TABLE_CONTACTS, KEY_ID + " = ?", 
       new String[] { String.valueOf(contact.getID()) }); 
     db.close(); 
    } 

} 

你能幫助我嗎？

Answer 1

選擇所有數據：函數返回光標下方。您必須從光標獲得價值並根據您的要求展示。

public Cursor selectAll() { 

    String query = "SELECT * FROM TBLevels"; 
    System.out.println(query); 
    cur = db.rawQuery(query, null); 

    cur.moveToFirst(); 
    return cur; 

} 

顯示值： -

 Routines r=new Routines(PhaseBuilder.this); 
     r.open(); 
     Cursor cr=r.selectAll(); 
     for(int i=0;i<cr.getCount();i++) 
     { 
      System.out.println(cr.getString(0));// 0 indicate your column 
      System.out.println(cr.getString(1));// 1 indicate your column 
      cr.moveToNext(); 
     } 
     cr.close(); 
     r.close(); 

選擇特定的數據

public Cursor getrecord(String LEVELID) { 
    //Log.e("we are", "TBLevels"); 
    Cursor mCursor = db.query("TBLevels", new String[] { 
      TB_LEVELID, TB_LEVELTEXT }, 
      TB_LEVELID + "=" + "'" + LEVELID 
      + "'", null, null, null, null, null); 
    if (mCursor != null) { 
     mCursor.moveToFirst(); 
    } 
    return mCursor; 
} 

刪除數據

public void deleteId(String ROUTINEID) 
    { 
     try 
     { 
      db.delete("TBRoutines", TB_ROUTINEID + "=" + ROUTINEID, null); 
     } 
     catch (Exception e) 
     { 
      // TODO: handle exception 
      System.out.println("deleteId RW"); 
      e.printStackTrace(); 
     } 
    }