There is a site on Joomla, there is a form component FormCalc. A form with a calculator, in general, is necessary after the user has selected what is needed, ticked, and when the send button was pressed, a letter arrived with exactly these checkboxes that he selected.
Form in HTML and JS. Sql is not involved.
Thank you in advance!
Set the name attribute for checkboxes of the array type (name=”array”) and then on the page where the form is sent, you can catch this array in $_REQUEST, which will contain the values of all checked checkboxes