public function uniqueKey(array $colNames, /*# string */ $extraClause = '')
    {
        if (!isset($this->tbl_constraint['unique'])) {
            $this->tbl_constraint['unique'] = [];
        }
        $this->tbl_constraint['unique'][] = [$colNames, $extraClause];
        return $this;
    }
public function uniqueKey(array $colNames, /*# string */ $extraClause = '')
    {
        if (!isset($this->tbl_constraint['unique'])) {
            $this->tbl_constraint['unique'] = [];
        }
        $this->tbl_constraint['unique'][] = [$colNames, $extraClause];
        return $this;
    }
{@inheritDoc}