How does \Zend_Db_Select::group() work?

dmitrii_fediuk · April 29, 2016, 6:54pm

Context: How does \Magento\Eav\Model\ResourceModel\Entity\Attribute\Collection::addAttributeGrouping() work?

zendframework/zf1/blob/release-1.12.16/library/Zend/Db/Select.php#L501-L521


/**
 * Adds grouping to the query.
 *
 * @param  array|string $spec The column(s) to group by.
 * @return Zend_Db_Select This Zend_Db_Select object.
 */
public function group($spec)
{
    if (!is_array($spec)) {
        $spec = array($spec);
    }


    foreach ($spec as $val) {
        if (preg_match(self::REGEX_COLUMN_EXPR, (string) $val)) {
            $val = new Zend_Db_Expr($val);
        }
        $this->_parts[self::GROUP][] = $val;
    }


    return $this;
}