public function isUniqueValue($strTable, $strField, $varValue, $intId=null)
	{
		$strQuery = "SELECT * FROM $strTable WHERE " . static::quoteIdentifier($strField) . "=?";

		if ($intId !== null)
		{
			$strQuery .= " AND id!=?";
		}

		$objUnique = $this->prepare($strQuery)
						  ->limit(1)
						  ->execute($varValue, $intId);

		return $objUnique->numRows ? false : true;
	}