/**
* linked parent and child relation
*
* @param NodeInterface $descendant child node instance
* @param NodeInterface $ancestor parent node instance
* @return bool
*/
public function linkHierarchy(NodeInterface $descendant, NodeInterface $ancestor)
{
$prefix = $this->conn->getTablePrefix();
$expression = $this->conn->raw(implode(' ', ["insert into {$prefix}{$this->hierarchyTable} (`ancestor`, `descendant`, `depth`) ", "select a.`ancestor`, d.`descendant`, a.`depth` + d.`depth` + 1 ", "from {$prefix}{$this->hierarchyTable} a, {$prefix}{$this->hierarchyTable} d ", "where a.`descendant` = '{$ancestor->id}' and d.`ancestor` = '{$descendant->id}'"]));
return $this->conn->statement($expression);
}
