For that you have to add attribute mouserover and mouseout of Gridview row.
You can assign this attribute
on OnRowDataBound
Event of gridview.
Code Snippet:
.aspx code:
<asp:GridView ID="GridView1"
runat="server"
AutoGenerateColumns="False"
DataSourceID="SqlDataSource1" OnRowDataBound="bound"
BackColor="Silver"
onselectedindexchanged="GridView1_SelectedIndexChanged" >
<Columns>
<asp:BoundField DataField="date" HeaderText="date" SortExpression="date" />
<asp:BoundField DataField="empolyeeno" HeaderText="empolyeeno"
SortExpression="empolyeeno" />
<asp:BoundField DataField="location" HeaderText="location"
SortExpression="location" />
<asp:BoundField DataField="position" HeaderText="position"
SortExpression="position" />
</Columns>
</asp:GridView>
.apx.cs code
Protected void bound(object sender, GridViewRowEventArgs e)
{
e.Row.Attributes.Add("onmouseover", "style.backgroundColor='#ffffff'");
e.Row.Attributes.Add("onmouseout", "style.backgroundColor='#C0C0C0'");
}