Android Sqlite Update增加了价值问题

Question

问题是以下代码第一次更新列值时工作得很好，但是下次拒绝增加它。

public void incrementValue(Context context, String number) {

     SwipeDatabaseHelper mOpenHelper = new SwipeDatabaseHelper(
          context.getApplicationContext());

     String sql = "UPDATE " + DatabaseContract.PATH_CONTACTS + " SET "
          + DatabaseContract.DatabaseEntry.COLUMN_CONTACT_UNREAD + " = " +
          DatabaseContract.DatabaseEntry.COLUMN_CONTACT_UNREAD + " + 1 WHERE "
          + DatabaseContract.DatabaseEntry.COLUMN_CONTACT_NUM + " = ?";

     mOpenHelper.getWritableDatabase().execSQL(sql, new String[]{number});
}

非常有趣的是，当我用硬编码值（例如0）更新它时，它完美无缺。当我再次调用该函数时，它只会将其递增1，即使您将其调用一千次，该值也不会超过1

public class DatabaseHelper extends SQLiteOpenHelper {
  private final static String DATABASE_NAME = "persistent.db";
  private final static int CUR_DATABASE_VERSION = 4;

  public SwipeDatabaseHelper(Context context) {
      super(context, DATABASE_NAME, null, CUR_DATABASE_VERSION);
  }

  @Override
  public void onCreate(SQLiteDatabase db) {

    final String CONTACTS = "CREATE TABLE USER (" +
        DatabaseEntry._ID +" INTEGER PRIMARY KEY AUTOINCREMENT," +
        DatabaseEntry.COLUMN_CONTACT_NUM + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_CONTACT_NAME + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COULUMN_CONTACT_SURNAME + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_CONTACT_USERNAME + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_CONTACT_UNREAD + " INTEGER NOT NULL DEFAULT 0," +
        DatabaseEntry.COLUMN_CONTACT_URL + " TEXT NOT NULL DEFAULT ''," +
        "UNIQUE(" + DatabaseEntry.COLUMN_CONTACT_NUM + ") ON CONFLICT REPLACE);";

    final String GROUPS = "CREATE TABLE GROUPS (" +
        DatabaseEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT," +
        DatabaseEntry.COLUMN_CONTACT_NUM + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_GROUP_NAME + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_GROUP_IMAGE + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_GROUP_OWNER + " TEXT NOT NULL DEFAULT ''," +
        DatabaseEntry.COLUMN_CONTACT_UNREAD + " INTEGER NOT NULL DEFAULT 0," +
        "UNIQUE(" + DatabaseEntry.COLUMN_CONTACT_NUM + ") ON CONFLICT REPLACE);";

    db.execSQL(CONTACTS);
    db.execSQL(GROUPS);

  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    db.execSQL("DROP TABLE IF EXISTS USER");
    db.execSQL("DROP TABLE IF EXISTS GROUPS");
    onCreate(db);
  }
}

因此同一个调用适用于User表，但对于Groups表行为异常。