buttton event....

HI frinds  i Have a urgent question..

 

I have button click event .. when i am clicking the button(only once) its doing fine..

but when i click 2 or 3 times continusly its thrwoing an error messge or its not doing any thing (bec its creating session 2 or 3 times)

I need when i click the button once I need to disable the button so that user does not click two or more than that..

Thanks..
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