See in this article we have done different types of databinding in dropdownlist,
1. Manual Binding like Gender (Male, Female)
2. Database binding from from sql to dropdownlist that is Country binding
3. Using Jquery and sql with filteration country and state binding state and city
For that you have read carefully all of things in this artile which will help you a lot. Hope so
Dropdownlist, Cascading Dropdown[^]