title: error when deleting in sqlite database
body: <p>Im new in terms of coding, So I copy paste the codes of some tutorials, but when Im trying to delete all data in the "sleep" column, this error is showing. </p>
  
  <blockquote>
    <p>android.database.sqlite.SQLiteException: near "20170128": syntax error
    (code 1): , while compiling: DELETE FROM 20170128
                                                         at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native
    Method)
                                                         at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
                                                         at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
                                                         at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
                                                         at android.database.sqlite.SQLiteProgram.(SQLiteProgram.java:58)
                                                         at android.database.sqlite.SQLiteStatement.(SQLiteStatement.java:31)
                                                         at android.database.sqlite.SQLiteDatabase.delete(SQLiteDatabase.java:1496)
                                                         at jm.myapplication.Sleep.sleep_repo.delete1(sleep_repo.java:51)
                                                         at jm.myapplication.Main.MainActivity$1.onClick(MainActivity.java:220)
                                                         at android.view.View.performClick(View.java:4780)
                                                         at android.view.View$PerformClick.run(View.java:19866)
                                                         at android.os.Handler.handleCallback(Handler.java:739)
                                                         at android.os.Handler.dispatchMessage(Handler.java:95)
                                                         at android.os.Looper.loop(Looper.java:135)
                                                         at android.app.ActivityThread.main(ActivityThread.java:5254)
                                                         at java.lang.reflect.Method.invoke(Native Method)
                                                         at java.lang.reflect.Method.invoke(Method.java:372)
                                                         at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                         at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)</p>
  </blockquote>
  
  <p>This is my codes.</p>
  
  <p>This is on my main activity</p>
  
  <pre><code>public void onClick(View v) {
                  final Integer newSleep = sleep;
                      sleep_repo repo = new sleep_repo(MainActivity.this);
                      others sleep = new others();
  
                       sleep.sleep = Recent_f_id;
                       sleep.sleep=newSleep;
  
      repo.delete1(sleep);
  
      Recent_f_id = repo.insert(sleep);
  
      Toast.makeText(getApplicationContext(),
              newSleep + " has been added", Toast.LENGTH_LONG)
              .show();
      d.dismiss();
   }
  </code></pre>
  
  <p>while this is my sleep_repo.java</p>
  
  <pre><code>public void delete1(others sleep) {
  
          // db.delete(String tableName, String whereClause, String[] whereArgs);
          // If whereClause is null, it will delete all rows.
          SQLiteDatabase db = dbHelper.getWritableDatabase(); // helper is object extends SQLiteOpenHelper
          db.delete(getDateTime(),null,null);
          /*db.delete(getDateTime(),others.KEY_ID+"=?",new String[] { String.valueOf(sleep) });*/
          db.close(); // Closing database connection
      }
  </code></pre>
  
  <p>while this is my others.java</p>
  
  <pre><code>public class others {
  
      // Labels table name
      public static final String TABLE = "others";
  
      // Labels Table Columns names
      public static final String KEY_ID = "id";
      public static final String KEY_sleep = "sleep";
      public static final String KEY_smoke = "smoke";
      public static final String KEY_exercise = "exercise";
  
  
  
  
  
      // property help us to keep data
      public int Recent_f_id;
      public Integer id;
      public Integer sleep;
      public Integer smoke;
      public String exercise;
  
  
  }
  </code></pre>
  
  <p>and this is my Dates.java</p>
  
  <pre><code>public class Dates extends SQLiteOpenHelper {
      //version number to upgrade database version
      //each time if you Add, Edit table, you need to change the
      //version number.
      private static final int DATABASE_VERSION = 4;
  
  
  
      public static String getDateTime() {
          SimpleDateFormat dateFormat = new SimpleDateFormat(
                  "yyyyMMdd", Locale.getDefault());
          Date date = new Date();
          return dateFormat.format(date);
      }
  
      // Database Name
      private static final String DATABASE_NAME = getDateTime();
  
      public Dates(Context context ) {
          super(context, DATABASE_NAME, null, DATABASE_VERSION);
      }
  
  
      @Override
      public void onCreate(SQLiteDatabase db) {
          //All necessary tables you like to create will create here
  
          String CREATE_TABLE_meals = "CREATE TABLE " + meals.TABLE  + "("
                  + meals.KEY_breakfast + " TEXT, "
                  + meals.KEY_lunch + " TEXT, "
                  + meals.KEY_dinner + " TEXT, "
                  + meals.KEY_other   + " TEXT )";
  
          String CREATE_TABLE_drinks = "CREATE TABLE " + drinks.TABLE  + "("
                  + drinks.KEY_alcoholic + " TEXT, "
                  + drinks.KEY_water  + " INTEGER )";
  
          String CREATE_TABLE_others = "CREATE TABLE " + others.TABLE  + "("
                  + others.KEY_ID  + " INTEGER PRIMARY KEY AUTOINCREMENT ,"
                  + others.KEY_sleep + " TEXT, "
                  + others.KEY_smoke + " INTEGER, "
                  + others.KEY_exercise   + " INTEGER )";
  
          db.execSQL(CREATE_TABLE_meals);
          db.execSQL(CREATE_TABLE_drinks);
          db.execSQL(CREATE_TABLE_others);
  
      }
  </code></pre>