asp.net中按钮点击发送短信功能，短信内容不能从数据库里提取到，这是怎么回事？

我网站采用的是三层架构，以下是在UI的cs页面上按钮点击事件
mysql语句已验证过，语句没问题
然后我在想，这个问题肯定是没有连接上数据库导致没查询，请问怎么加上连接数据库的代码呢？

 protected void sndsms_Click(object sender, EventArgs e)
        {
            string cont="";
            string str;
            string phones = "XXXXXXXXXX";
            string content = "";
            content = "系统：";
            content += cont;
            cont = @"SELECT a.NZLID as NozzleID,concat(Round(a.LASTAVG*100,2) ,'%') as `ErrorRate(%)`,
                                h.NZLERR-h.LASTERR as NozzleErr,
                                a.MACHINE,a.NZLMODULENO
                                FROM T_NZLMST4 a 
                                left join (select NZLID,NZLTOTALCNT,LASTCNT,NZLERR,LASTERR from T_NZLHIS4 b inner join 
                                (select max(id) as id from T_NZLHIS4 group by NZLID) c on b.id = c.id) h on a.NZLID=h.NZLID 
                                Order By case when h.NZLTOTALCNT=h.LASTCNT then 1 else 0 end,LASTAVG desc;";
            str = "短信服务商提供的接口“
            str += phones;
            str += "&msg=";
            str += content;

            HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(str);
            req.Method = "GET";

            HttpWebResponse response = req.GetResponse() as HttpWebResponse;
            Stream respStream = response.GetResponseStream();
            StreamReader respStreamReader = new StreamReader(respStream, Encoding.UTF8);
            string result = respStreamReader.ReadToEnd();
            //return strBuff; 
            if (result != "发送成功")
                Console.WriteLine("发送失败");
            else
                Console.WriteLine("发送成功");  
        }

没看到你执行sql的逻辑。
你应该写 SqlCommand cmd = new SqlCommand(连接);
var reader = cmd.ExecuteReader();
while (reader.Read())
{
读取数据库返回的内容
}