<div><asp:textboxid="txt1"text="sheraj"style=" text-decoration:blur"runat="server"></asp:textbox><asp:requiredfieldvalidatorid="r1"controltovalidate="txt1"errormessage="error1"validationgroup="btng"runat="server"></asp:requiredfieldvalidator><asp:textboxid="txt2"runat="server"></asp:textbox>
--here u need to use two RequiredFieldValidatorfro 2nd text box
<asp:requiredfieldvalidatorid="RequiredFieldValidator1"controltovalidate="txt2"errormessage="error1"validationgroup="bt1"runat="server"></asp:requiredfieldvalidator><asp:requiredfieldvalidatorid="RequiredFieldValidator2"controltovalidate="txt2"errormessage="error2"validationgroup="bt2"runat="server"></asp:requiredfieldvalidator><asp:buttonid="btn1"runat="server"validationgroup="bt1"text="insert "></asp:button><asp:buttonid="btn2"runat="server"validationgroup="bt2"text="update"></asp:button><asp:buttonid="btn3"runat="server"causesvalidation="false"text="some opretion"></asp:button></div>