src/Db/DataReader.php
public function readColumn($columnIndex)
    {
        $this->next();
        if (!$this->valid()) {
            return false;
        }
        return $this->_command->fetchResultsRow($this->_row, CommandInterface::FETCH_FIELD, CommandInterface::FETCH_MODE_ASSOC, $columnIndex);
    }
public function readColumn($columnIndex)
    {
        $this->next();
        if (!$this->valid()) {
            return false;
        }
        return $this->_command->fetchResultsRow($this->_row, CommandInterface::FETCH_FIELD, CommandInterface::FETCH_MODE_ASSOC, $columnIndex);
    }
Returns a single column from the next row of a result set.
@param int $columnIndex zero-based column index
@return mixed the column of the current row, false if no more rows available