protected function buildValuesClause() {
		if (!empty($this->expression))
			return $this->expression;
		
		if (empty($this->value)) {
			$values = [];
			
			for ($i = 0, $n = count($this->valueList); $i < $n; $i++)
				$values[] = '%{' . $i . '}';
			
			return implode(',', $values);
		}
		

		$values = [];
		
		foreach ($this->columnList as $column) {
			$name = $this->parseColumn($column);
			$values[] = '#{' . $name . '}';
		}

		return implode(',', $values);
	}