src/Wrappers/PDOWrapper.php
public function getColumn($query, array $arguments = array(), $column_number = 0)
  {
    return $this->run($query, $arguments)->fetchColumn($column_number);
  }
public function getColumn($query, array $arguments = array(), $column_number = 0)
  {
    return $this->run($query, $arguments)->fetchColumn($column_number);
  }
PDO::prepare()::execute()::fetchColumn() chaining wrapper.

@param string SQL query with placeholders.
@param array substitution variables.
@param int column number to retrieve value from.
@return mixed value of the $column_number's column from the first row of the resultset.

@see PDO::prepare()
@see PDOStatement::execute()
@see PDOStatement::fetchColumn()