ASP GridView Bulk Delete and select all

I novice just learned to select and delete all of the code is also quoted other people's codes to try a try can be achieved, feel good, sent up.

Front Code

<asp:gridview id= "GridView1" runat= "Server" allowsorting= "True" autogeneratecolumns= "False"
cellpadding= " 3 "font-size=" 9pt "backcolor=" white "bordercolor=" #CCCCCC "
borderstyle=" None "borderwidth=" 1px "width=" 675px "
onrowdatabound= "GridView1_RowDataBound" datakeynames= "Project id"
;
<footerstyle backcolor= "White" Forecolor= "#000066"/>
<columns>
<asp:templatefield headertext= "select";
<itemtemplate
<asp:checkbox id= "CheckBox1" runat= "Server"/>
</itemtemplate>
</asp:templatefield
<asp:boundfield datafield= "project name" headertext= "project name"/>
<asp:boundfield datafield= "project status" headertext= "project status"/>
<asp:templatefield headertext= "verbose";
<itemtemplate>
<a href= Detailed.aspx?id= ' <% #Eval ("Project ID")%> ' ",
<asp:label id=" lbl verbose "runat=" server "text=" verbose "></asp: Label></a>
</itemtemplate>
</asp:templatefield>

<asp:templatefield headertext= "Edit" >
<ItemTemplate>
<a href= "editproject.aspx?id= ' <% #Eval (" Project ID ")%> '" >
<asp:label id= "LbL edit" runat= "Server" text= "edit" ></asp:Label></a>
</ItemTemplate>
</asp:TemplateField>

</Columns>
<rowstyle forecolor= "#000066"/>
<selectedrowstyle backcolor= "#669999" font-bold= "True" forecolor= "white"/>
<pagerstyle backcolor= "White" forecolor= "#000066" horizontalalign= "left"/>
</asp:GridView>

Background code

Using System;
Using System.Collections.Generic;
Using System.Linq;
Using System.Web;
Using System.Web.UI;
Using System.Web.UI.WebControls;
Using System.Data;
Using System.Data.SqlClient;

public partial class _default:system.web.ui.page
{

protected void Page_Load (object sender, EventArgs e)
{

if (! IsPostBack)
{
Bind ();
}
}

public void bind ()
{
SqlConnection con = new SqlConnection ("server=.; Database= Poll Survey database; uid=sa;pwd=401 ");
String sql = "SELECT * from Project table";
SqlCommand com = new SqlCommand (sql, con);
SqlDataAdapter da = new SqlDataAdapter (COM);
DataSet ds = new DataSet ();
Da. Fill (DS);
Gridview1.datasource = ds;
Gridview1.databind ();
}
Select All
protected void Checkbox2_checkedchanged (object sender, EventArgs e)
{
for (int i = 0; I <= gridview1.rows.count-1; i++)
{
CheckBox Cbox = (checkbox) Gridview1.rows[i]. FindControl ("CheckBox1");
if (checkbox2.checked = = True)
{
Cbox. Checked = true;
}
Else
{
Cbox. Checked = false;
}
}
}
Select All to cancel
protected void Button1_Click (object sender, EventArgs e)
{
checkbox2.checked = false;
for (int i = 0; I <= gridview1.rows.count-1; i++)
{
CheckBox Cbox = (checkbox) Gridview1.rows[i]. FindControl ("CheckBox1");
Cbox. Checked = false;
}
}
Delete
protected void button2_click (object sender, EventArgs e)
{

String sql = "Delete from project table where";
String cal = "";
for (int i = 0; i < GridView1.Rows.Count; i++)
{
CheckBox Cbox = (checkbox) Gridview1.rows[i]. Cells[0]. FindControl ("CheckBox1");
if (Cbox. Checked = = True)
{
Cal + = "Project id=" + gridview1.datakeys[i]. Value.tostring () + "or";
}
}
if (cal! = "")
{
SQL + = Cal. Substring (0, Cal. LENGTH-3);
}
Else
{sql = "";}
Response.Write (SQL);//You can define your own programs here to delete tasks
SqlConnection con = new SqlConnection ("server=.; Database= Poll Survey database; uid=sa;pwd=401 ");
Con. Open ();
SqlCommand com = new SqlCommand (sql, con);
Com. ExecuteNonQuery ();
Bind ();

}
Inquire
protected void Button1_click1 (object sender, EventArgs e)
{
SqlConnection con = new SqlConnection ("server=.; Database= Poll Survey database; uid=sa;pwd=401 ");
String name = this. TextBox1.Text;

String sql = "SELECT * from Project table where item id= '" + TextBox1.Text + "'";

SqlCommand cmd = new SqlCommand (sql, con);
SqlDataAdapter da = new SqlDataAdapter (cmd);
DataSet ds = new DataSet ();
Da. Fill (DS);
Gridview1.datasource = ds;
Gridview1.databind ();
}

protected void GridView1_RowDataBound (object sender, GridViewRowEventArgs e)
{
if (E.row.rowtype = = Datacontrolrowtype.datarow)
{
E.row.attributes.add ("onmouseover", "if (this!=prevselitem) {this.style.backgroundcolor= ' #Efefef '}");// Change the background color when the mouse rests
E.row.attributes.add ("onmouseout", "if (this!=prevselitem) {this.style.backgroundcolor= ' #ffffff '}"), and//restore the background color when the mouse is moved away
E.row.attributes.add ("onclick", e.row.clientid.tostring () + ". Checked=true;selectx (This)");//click the line Color

e.row.attributes["style"] = "Cursor:hand"; Set the hover mouse pointer shape to "small hands"

}
}
protected void Button4_Click (object sender, EventArgs e)
{
Response.Redirect ("add.aspx");
}
}

ASP GridView Bulk Delete and select all