c＃.aspx页面记录导航

Question

我有一个简单的.aspx页面，带有导航按钮但是虽然First＆amp;最后一个按钮工作正常，下一个＆amp;以前只在记录1和1之间移动2由于某种原因，我无法解决。 我仍然是C＃和ASP.NET的新手，但这看起来很基本，令人尴尬！ 我正在使用SQL Server 2012和Visual Studio 2017。 这很奇怪，因为记录计数确认所有记录都已被读取。

C# Code:
        SqlCommand cmd = new SqlCommand();
        SqlDataAdapter da = new SqlDataAdapter();
        //
        SqlDataReader dr;
        DataSet ds;
        int recordcount = 0;
        int i;
        SqlConnection con = new SqlConnection(@"Data Source=ASPIREV17;Initial Catalog=dbSVCCAssets;Integrated Security=True");

        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(@"Data Source=ASPIREV17;Initial Catalog=dbSVCCAssets;Integrated Security=True");
            cmd = new SqlCommand("SELECT * FROM SignboardInspection", con);
            da = new SqlDataAdapter(cmd);
            ds = new DataSet();

            con.Open();
            da.Fill(ds, "SignboardInspection");
            Response.Write("Connection is Open Now!!");
            dr = cmd.ExecuteReader();
            recordcount = ds.Tables[0].Rows.Count;
            Response.Write("Record Count : " + recordcount);

            if (recordcount > i)
            {
                TextBox1.Text = ds.Tables[0].Rows[i]["ID"].ToString();
                TextBox2.Text = ds.Tables[0].Rows[i]["DateInspected"].ToString();
                TextBox3.Text = ds.Tables[0].Rows[i]["NextInspection"].ToString();
                TextBox4.Text = ds.Tables[0].Rows[i]["Comments"].ToString();
            }
            else
            {
                lblMessage.Text = ("No Records Returned");
            }
            dr.Read();

            con.Close();
            Response.Write("Connection is Closed Now!!");
        }

        protected void btnFirst_Click(object sender, EventArgs e)
        {
            if (ds.Tables[0].Rows.Count > 0)
            {
                i = 0;
                TextBox1.Text = ds.Tables[0].Rows[i]["ID"].ToString();
                TextBox2.Text = ds.Tables[0].Rows[i]["DateInspected"].ToString();
                TextBox3.Text = ds.Tables[0].Rows[i]["NextInspection"].ToString();
                TextBox4.Text = ds.Tables[0].Rows[i]["Comments"].ToString();
            }
            else
            {
                lblMessage.Text = ("First Record");
            }
        }

        protected void btnNext_Click(object sender, EventArgs e)
        {
            if (i < ds.Tables[0].Rows.Count - 1)
            {
                i++;
                TextBox1.Text = ds.Tables[0].Rows[i]["ID"].ToString();
                TextBox2.Text = ds.Tables[0].Rows[i]["DateInspected"].ToString();
                TextBox3.Text = ds.Tables[0].Rows[i]["NextInspection"].ToString();
                TextBox4.Text = ds.Tables[0].Rows[i]["Comments"].ToString();
            }
            else
            {
                lblMessage.Text = ("This is the Last Record");
            }
        }

        protected void btnPrevious_Click(object sender, EventArgs e)
        {
        if (i == ds.Tables[0].Rows.Count - 1)
        {
            i--;
            TextBox1.Text = ds.Tables[0].Rows[i]["ID"].ToString();
            TextBox2.Text = ds.Tables[0].Rows[i]["DateInspected"].ToString();
            TextBox3.Text = ds.Tables[0].Rows[i]["NextInspection"].ToString();
            TextBox4.Text = ds.Tables[0].Rows[i]["Comments"].ToString();
        }
        else
        {
                lblMessage.Text = ("This is the First Record");
        }
    }

请建议并保持温和！