<style type="text/css">
            #GridView1 tr.rowHover:hover
            {
                background-color: Yellow;
                font-family: Arial;
            }
        </style>
        <asp:GridView ID="GridView1" runat="server" EnableViewState="false" RowStyle-CssClass="rowHover" />

Code Behind

string _connStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        GetData();
    }
}
private void GetData()
{
    DataTable table = new DataTable();
    // get the connection
    using (SqlConnection conn = new SqlConnection(_connStr))
    {
        // write the sql statement to execute
        string sql = "SELECT AutoId, FirstName, LastName, Age, Active FROM PersonalDetail ORDER By AutoId";
        // instantiate the command object to fire
        using (SqlCommand cmd = new SqlCommand(sql, conn))
        {
            // get the adapter object and attach the command object to it
            using (SqlDataAdapter ad = new SqlDataAdapter(cmd))
            {
                // fire Fill method to fetch the data and fill into DataTable
                ad.Fill(table);
            }
        }
    }
    // specify the data source for the GridView
    GridView1.DataSource = table;
    // bind the data now
    GridView1.DataBind();
}