try in the same way
<asp:RadioButtonList ID="rb_Isfresher" RepeatDirection="Horizontal" runat="server"
OnSelectedIndexChanged="rb_Isfresher_SelectedIndexChanged" AutoPostBack="true">
<asp:ListItem Text="Yes" Value="0" Selected="True">
<asp:ListItem Text="No" Value="1">
//in the code behind
Boolean strIsFresher ;
if (rb_Isfresher.SelectedValue == "1")
{
strIsFresher = true;
}
else
{
strIsFresher = false;
}
// Send Boolean value to the Database