In this Article you can Know how to get a Multiple selected values using CheckBox
First Drag and Drop one Gridvew and Button on asp Page.Later Retrive the Data From a Table on Gridview,by using Bound field and Add on CheckBox field in .aspx source code page as Below.
<asp:GridView id="Gridview1" runat ="server" AutoGenerateColumns ="False" ShowFooter ="True" DataSourceID ="SqlDataSource1" OnSelectedIndexChanged="Gridview1_SelectedIndexChanged" style="z-index: 101; left: 19px; position: absolute; top: 142px" BackColor="LightGoldenrodYellow" BorderColor="Tan" BorderWidth="1px" CellPadding="2" ForeColor="Black" GridLines="None" Width="240px" >
<Columns >
<asp:TemplateField >
<ItemTemplate >
<asp:CheckBox ID="chk" runat ="server" />
</ItemTemplate>
</asp:TemplateField>
<asp:BoundField DataField ="ID" HeaderText ="ID" />
<asp:BoundField DataField="empname" HeaderText ="Name" />
<asp:BoundField DataField ="salary" HeaderText ="Salary" />
</Columns>
<FooterStyle BackColor="Tan" />
<SelectedRowStyle BackColor="DarkSlateBlue" ForeColor="GhostWhite" />
<PagerStyle BackColor="PaleGoldenrod" ForeColor="DarkSlateBlue" HorizontalAlign="Center" />
<HeaderStyle BackColor="Tan" BorderColor="Fuchsia" BorderStyle="Solid" Font-Bold="True" />
<AlternatingRowStyle BackColor="PaleGoldenrod" />
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
ProviderName="<%$ ConnectionStrings:ConnectionString.ProviderName %>" SelectCommand="SELECT [ID], [empname], [salary] FROM [emp]">
</asp:SqlDataSource>
The output Image of Above code is Below:

Now i am writing code in GetValues Button to retrive values when the user selects one or more CheckBoxes.
protected void GetValues_Click(object sender, EventArgs e)
{
for (int i = 0; i < Gridview1.Rows.Count; i++)
{
CheckBox chkb = (CheckBox)Gridview1.Rows[i].Cells[0].FindControl("chk");
if (chkb.Checked)
{
string name = Gridview1.Rows[i].Cells[2].Text;
Response.Write("<br>" + name);
}
}
}
Click on GetValues Button After selecting
one or more CheckBoxes, then you will get Values what you had checked in gridview.
The OutPut Of Image is Below:
