数据库连接 调用线程

 private void button1_Click(object sender, EventArgs e)
        {

             Thread th = new Thread(new ThreadStart(doo));
            th.Start();
        }

        private void doo()
        {
            SqlConnection conn = new SqlConnection("server=114.80.209.183;database=ichat33;uid=sa;pwd=123456;");
            SqlCommand cmd = new SqlCommand();
            cmd.Connection = conn;
            conn.Open();
            cmd.CommandText = "select [username],[userpassword] from userinfo ";
            DataSet ds = new DataSet();
            SqlDataAdapter sda = new SqlDataAdapter(cmd);

            sda.Fill(ds);
            conn.Close();
            DataTable dt = ds.Tables[0];

            SqlConnection connN = new SqlConnection("server=114.80.209.183;database=chat;uid=sa;pwd=123456;");
            connN.Open();
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                try
                {
                    cmd = new SqlCommand("insert into [user]([name],[passwd]) values('" + dt.Rows[i]["username"].ToString() + "','" + dt.Rows[i]["userpassword"].ToString() + "')   ", connN);
                    cmd.Connection = connN;
                   
                    int result = cmd.ExecuteNonQuery();
                    if (result == 1)
                    {
                        label1.Text = "成功导入" + (i + 1).ToString() + " " + dt.Rows[i]["username"].ToString();
                    }
                }catch(Exception ex){continue;}

            }

            conn.Close();
        }