insert date with a calendar

Hi there. I have an app that requires users to insert an 'end' date. The date is saved in MYSQL in the date format. The problem is that the user input, which is not always reliable, has to be in the correct format. I was wondering if there is a way to have a simple calendar option, either on the page on in a pop-up window, where a user can select a date which will then have the correct format to be inserted. There is also other data being captured on this page so this preferably needs to be done without refreshing the page. Any ideas would be greatly appreciated. Thanks Kevin