Build the query based upon the formula
Overrides ArgumentPluginBase::query
public function query($group_by = FALSE) {
$this
->ensureMyTable();
// Now that our table is secure, get our formula.
$placeholder = $this
->placeholder();
$formula = $this
->get_formula() . ' = ' . $placeholder;
$placeholders = array(
$placeholder => $this->argument,
);
$this->query
->add_where(0, $formula, $placeholders, 'formula');
}