Zend Column not found: 1054 Unknown column '0' in 'field list'

[bengali]

I have a next code:\[code\] $parent_priority = $data['priority']; $where = $this->getAdapter()->quoteInto('priority >= ?', $parent_priority); $columns = array ('id', 'title', 'enabled', 'description', 'pv', 'gv', 'mps', 'priority', ); $select_data = http://stackoverflow.com/questions/3557191/$this->select()->from($this->_name, $columns); $ranks = $this->fetchAll($select_data)->toArray();\[/code\]But Zend create an error "Column not found: 1054 Unknown column '0' in 'field list'" in line \[code\]$ranks = $this->fetchAll($select_data)->toArray();\[/code\]How I can solve this?