code: public boolean hasTag(String tag, SPFPersona persona) {
  		SQLiteDatabase db = getReadableDatabase();
  		String selection = Contract.COLUMN_VALUE + " LIKE ? AND " + Contract.COLUMN_PERSONA + " = ? ";
  		String[] selectionArgs = { "%" + tag + "%", persona.getIdentifier() };
  		String[] columns = { Contract.COLUMN_KEY };
  		String groupBy = null;
  		String having = null;
  		String orderBy = null;
  		String limit = null;
  		Cursor c = db.query(true, // distinct
  				Contract.TABLE_PROFILE, // table name
  				columns, // projection
  				selection, // selection
  				selectionArgs, // selection arguments
  				groupBy, // don't group the rows
  				having, // don't filter by row groups
  				orderBy, // don't order by anything
  				limit);
  
  		boolean match = c.moveToNext();
  		c.close();
  		return match;
  	}
docs: /** Check if the profile fields of a given SPFPersona contains the
  specified tag. Returns true when the tag is contained in at least one
  profile field value.
  
  @param tag
  @param persona
  @return true if the profile contains the tag