protected void btnBackUp_Click(object sender, EventArgs e)  
    {
        string ConnctionString = "Data Source=.;User ID=sa;Password=123;Database='" + this.dbName.SelectedValue + "'";
        string dbbackupfilepath = Server.MapPath("~/DBBackUpFile/DataBase");
        string strSQL = "backup database " + this.dbName.SelectedValue + " to disk='" + dbbackupfilepath + "\\" + this.tbPosition.Text.Trim() + ".bak'";
            

            try
        {
            //判断该路径下是否已经有该文件了
            if (File.Exists(dbbackupfilepath + "\\" + this.tbPosition.Text.Trim() + ".bak"))
            {
                //存在此文件，提示错误
                   ClientScript.RegisterClientScriptBlock(GetType(), "", "<script>alert('文件名已存在,请重新命名!');</script>");
                      return;
            }
            else
            {
                using (SqlConnection con = new SqlConnection(ConnctionString))
                {
                    con.Open();                  
                   
                    using (SqlCommand cmd = new SqlCommand(strSQL, con))
                        {
                            cmd.ExecuteNonQuery();
                            ClientScript.RegisterClientScriptBlock(GetType(), "", "<script>alert('数据库备份成功!');</script>");
                            
                        }
                 }
                  
                
            }
        }
        catch (Exception ex)
        {
            ClientScript.RegisterClientScriptBlock(GetType(), "", "<script>alert('备份数据库失败!原因是:" + ex.Message + "');</script>");
        }
    }