Avoid Multiple Form Submits

Multiple form submits can result difficulties in web applications because of unexpected behaviors like multiple entries in database. Here is a solution to help you avoid multiple submits.

If you are submitting the page only once then you can use,

<form onsubmit="return Submit();">

And the method is like,

<script type="text/javascript">
var flag = false;

function Submit()
{
 if (flag)
 {
   return false;
 }
 else
 {
  flag = true;
  return true;
 }
}
</script>

For a single button you can use,

btnSubmit.Attributes["onclick"] = "this.disabled=true;" +
GetPostBackEventReference(btnSubmit);

For pages with update panels multiple submit is a real problem as page is posting asynchronously or partially.In that scenario you can use Sys.WebForms.PageRequestManager for fixing the issue,

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

<script type="text/javascript">

Sys.WebForms.PageRequestManager.getInstance().add_beginRequest(BeginRequest);

function BeginRequest(sender, e)
{
e.get_postBackElement().disabled = true;
}

</script>