How can I add conditional logic for my Static HTML Form?

Question

https://code.sololearn.com/W3Yc144viuS0/?ref=app
I have created a static html form.
How do I create conditional logic for my code?

If i select Samsung than only samsung model (note 10 and 10 plus) should be displayed? Only “Samsung” and (on selecting model) “ note 10” should be submitted to MySql and php?

I don’t want my database/ php/ sql to receive data that was not shown? I don’t want to insert blank value as an option.

Answer 1

Hi, maybe this way:
https://code.sololearn.com/WxG348UsBcQJ/?ref=app
Try to select Samsung. Also consider that it is ES5 because it seems that my phone doesn't support ES6.

Answer 2

Sergei Romanov thanks for your answer. But when I submit won’t my php/sql server receive data of both iphone and samsung model?