ASP.net - GRIDVIEW with Button & HyperLink

<!--EVENT GRID VIEW [START]-->

<asp:GridView ID="gridView" DataKeyNames="SUBJECT_NAME" runat="server"

AutoGenerateColumns="False" HeaderStyle-Font-Bold="true"

BackColor="White" 

BorderColor="#CCCCCC" BorderStyle="Solid" BorderWidth="1px" CellPadding="3" 

                                    onselectedindexchanged="gridView_SelectedIndexChanged"

                                    CssClass="table table-hover table-bordered">

                            <Columns>  

                                <asp:BoundField DataField="SUBJECT_NAME" 

                                HeaderText="Subject" 

                                InsertVisible="False" ReadOnly="True" 

                                SortExpression="SUBJECT_NAME" />

                                <asp:BoundField DataField="CHAPTER_NAME" 

                                HeaderText="Chapter" 

                                SortExpression="CHAPTER_NAME" />

<asp:CommandField ButtonType="Button" HeaderText="Action" SelectText="Start Exam" ShowSelectButton="True" 

                                    ControlStyle-CssClass="btn btn-info" >

<ControlStyle CssClass="btn btn-info"></ControlStyle>

                                </asp:CommandField> 

<asp:hyperlinkfield 

datanavigateurlformatstring="~/StartExam.aspx?SUBJECT={0}&amp;CHAPTER={1}" 

datanavigateurlfields="SUBJECT_NAME,CHAPTER_NAME" Text="Start Exam" 

ControlStyle-CssClass="btn btn-info">

</asp:hyperlinkfield>                             

</Columns>

<FooterStyle BackColor="White" ForeColor="#000066" />

<HeaderStyle Font-Bold="True" BackColor="#006699" ForeColor="White"></HeaderStyle>

<PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" />

<RowStyle ForeColor="#000066" />

<SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />

<SortedAscendingCellStyle BackColor="#F1F1F1" />

<SortedAscendingHeaderStyle BackColor="#007DBB" />

<SortedDescendingCellStyle BackColor="#CAC9C9" />

<SortedDescendingHeaderStyle BackColor="#00547E" />

</asp:GridView>

<!--EVENT GRID VIEW [END]-->

OUTPUT SCREEN: