界面输入值和数据库值进行比较

    protected void Button1_Click(object sender, EventArgs e)
    {
        if (TextBox1.Text != "")
        {
            string strConnection = "server=.;database=colorring;uid=sa;pwd=";
            string strSql = "select   top 1 ringid   from  s50usersysringgrp   where   ringid=@ringid";
            SqlConnection con = new SqlConnection(strConnection);
            SqlCommand com = new SqlCommand(strSql, con);
            con.Open();

            com.Parameters.Add("@ringid", SqlDbType.Char, 12).Value = TextBox1.Text;
            SqlDataReader dr = com.ExecuteReader();
            if (dr.Read())
            {
                TextBox2.Text = "数据库中有该ringid";
            }
            else
            {
                TextBox2.Text = "数据库中没有该ringid";
            }
            dr.Close();
            con.Close();
        }
        else
        {
            TextBox2.Text = "你没有输入任何值";
        }

    }