How to Create Dynamic Dependent Dropdown Boxes Using jQuery, AJAX, PHP, and MySQL?

Creating Dynamic Dependent Dropdown Boxes Using jQuery/AJAX with PHP/MySQL

Aiming to create a dynamic set of dropdown boxes, you attempt to use jQuery/AJAX and PHP/MySQL. The objective is for the second dropdown to display values based on the selection in the first dropdown. Your HTML, PHP, and JavaScript code snippet highlights these efforts, but you encounter difficulties populating the second dropdown.

Adjusted Code for Success

To resolve the issue, your code requires some adjustments:

Modified document.ready:

$().ready(function() { // or $(function() {});

Revised Looping for JSON Result:

$.each(data.subjects, function(i, val){    
   $('select#item_2').append(`<option value="${val.id}">${val.name}</option>`);
});

Additional Considerations:

• Ensure the code included in the
  • MySQL Advanced 16 - Memory Optimization
  • mysql left, right, inner join
  • mysql null和‘ ’
  • mysql order by
  • mysql having