Question

这是我编写的从SQL Server获取数据并以标签显示数据的代码。我的目标是在数据库中更改数据时获取数据，该值应通过仅刷新文本在标签中显示。没有特定数量的标签要添加到表单，标签的数量与数据库中的行成正比。我正在动态创建标签，尽管出现了标签，但它们落后于上一个标签。

我想在出现新标签时清除以前的标签。

我做对了吗，哪里出了错？

private void timer1_Tick(object sender, EventArgs e)
{
    string connectionstring = "Data Source=DESKTOP;Initial Catalog=DB;Integrated Security=True";

    SqlConnection conn = new SqlConnection(connectionstring);
    conn.Open();            

    //MySqlConnection con = new MySqlConnection(myconnectionstring);
    string getdept = "SELECT tran_desc,sum(tran_qty) as qty FROM bill_tran group by tran_desc";

    SqlCommand cmd = new SqlCommand(getdept, conn);
    SqlDataAdapter adapter = new SqlDataAdapter(cmd);
    DataTable dt = new DataTable();
    adapter.Fill(dt);

    for (int z = 0; z < dt.Rows.Count; z++)
    {
        //MessageBox.Show(x.ToString());
        string nm = dt.Rows[z][0].ToString();
        string qty = dt.Rows[z][1].ToString();            

        string getdept2 = "SELECT item,sum(qty) AS TotalQuantity FROM temp_dayin where item='" + nm + "' group by item";

        System.Windows.Forms.Label txt = new System.Windows.Forms.Label();

        this.Controls.Add(txt);
        txt.Top = a * 28;
        txt.Left = 12;
        txt.Width = 600;
        txt.Height = 25;

        SqlCommand cmd2 = new SqlCommand(getdept2, conn);
        SqlDataAdapter adapter2 = new SqlDataAdapter(cmd2);
        DataTable dt2 = new DataTable();
        adapter2.Fill(dt2);
        string st = "";
        for (int x = 0; x < dt2.Rows.Count; x++)
        {
            string nm2 = dt2.Rows[x][0].ToString();
            string qty2 = dt2.Rows[x][1].ToString();
            //MessageBox.Show(nm + qty + nm2 + qty2);

            txt.Text = nm + qty2 + "-" + qty;
        }
        Controls.Add(txt);
        a += 1;
    }
}

private void Form3_Load(object sender, EventArgs e)
{
    timer1.Start();
}

Answer 1

可能是您可以做的，拥有一个面板并将所有标签添加到面板，在timer1_Tick下，我们可以清除面板中的所有控件并可以重新添加新标签。

private void timer1_Tick(object sender, EventArgs e)
{
    // clear all the controls under panel
    panel.Controls.Clear();

    // all your code to fetch the value from DB, and concatenate all
    // required columns to make your desired value.
    // set the label text as you value.
    // add labels to panel

    panel.Controls.Add(txt);
}

System.Windows.Forms.Panel panel = null;
private void Form3_Load(object sender, EventArgs e)
{
    timer1.Start();
    panel = new System.Windows.Forms.Panel();
    this.Controls.Add(panel);
}

在数据库值上使用计时器刷新标签文本

1 个答案: