Build the summary query based on a formula
Overrides ArgumentPluginBase::summary_query
function summary_query() {
$this
->ensureMyTable();
// Now that our table is secure, get our formula.
$formula = $this
->get_formula();
// Add the field.
$this->base_alias = $this->name_alias = $this->query
->add_field(NULL, $formula, $this->field);
$this->query
->set_count_field(NULL, $formula, $this->field);
return $this
->summary_basics(FALSE);
}