If you have any text box and you want to filter the record and display only selected record,

<asp:gridview id="GridView1" runat="server" datasourceid="SqlDataSource1" autogeneratecolumns="False">

<Columns>

<asp:BoundField DataField="FirstName" HeaderText="FirstName"

SortExpression="FirstName" />

<asp:BoundField DataField="SecondName" HeaderText="SecondName"

SortExpression="SecondName" />

<asp:BoundField DataField="ThirdName" HeaderText="ThirdName"

SortExpression="ThirdName" />

<asp:BoundField DataField="EmployeeID" HeaderText="EmployeeID"

SortExpression="EmployeeID" />

</Columns>

</asp:gridview>

<asp:sqldatasource id="SqlDataSource1" runat="server" connectionstring="<%$ ConnectionStrings:ConnectionString %>"

selectcommand="SELECT [FirstName], [SecondName], [ThirdName], [EmployeeID] FROM [Users] WHERE ([EmployeeID] = @EmployeeID)">

<SelectParameters>

<asp:ControlParameter ControlID="txtEmpID" Name="EmployeeID"

PropertyName="Text" Type="String" />

</SelectParameters>

</asp:sqldatasource>

In .CS file you can add

protected void btnShow_Click(object sender, EventArgs e)

{

ParameterCollection prm = SqlDataSource1.SelectParameters;

prm[0].DefaultValue = txtEmpID.Text;

}

Once you enter the number and hit the show button data will display in grid.