哪为 高手帮我看看下面代码怎么错了 老是删除失败！

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        string sql = "deletefrom book where k_id='" +Convert.ToInt32( this.TextBox1.Text)
            + "'and name='"
            + this.TextBox2.Text.ToString() + "'";
      
        if (DB.EN(sql)>=1)
        {
            Response.Write("删除成功");
        }
        else
        {
            Response.Write("删除失败");
        }

    }
}
DB类
using System;
using System.Data;
using System.Configuration;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

using System.Data.SqlClient;

/// <summary>
///DB 的摘要说明
/// </summary>
public class DB
{
    public DB()
    {
        //
        //TODO: 在此处添加构造函数逻辑
        //
    }
    public static int EN(string sqlstr)
    {
        int a=0;
        string str ="Data Source=7164BD0790E2444\\LIU;Initial Catalog=text;Integrated Security=True";
        SqlConnection con = new SqlConnection(str);
        SqlCommand cmd = new SqlCommand(sqlstr, con);
        try
        {
            a = cmd.ExecuteNonQuery();
            
        }
        catch (Exception e)
        {
         
        }
        finally
        {
            con.Close();
           
        }
        return a;