根据所选选项过滤值

I have two Dropdowns on my HTML. I want filtering values based on selected option. When a user click on a value of first dropdown, the value of another dropdown must be change. I know its simple, and yes you right its simple. But my options are inside my sql and i fill the options value of both of my dropdown from SQL. This is my Code:I have two Dropdowns on my HTML. I want filteri