在php中如何加载状态onchange

in mysql database I have a country table with id and country_name rows and state table with id, country_id and state_name rows . in php I want state drop down to load on country drop down selection.if anyone give me an example with two countries and two states it would be great.

For this you need a cliend side language like JS and server side language like PHP. You have to send request from client to server to send which country is selected. Check this and this