Prevent ImageButton to multiple postback.

Hi Every one,
I have the webapplication and in that I have on Imagebutton which is saving the data in database, but i got the issue when user click on multiple times(within a second) so in the data base multiple record are saving becuase of postback, i want to save only one time so please help me regarding if user click on button only first time i take the postback event and disable the image button untill data is saved.

Thanks for help.