c# - 如何在标签文本中显示计数？

Question

我很难将我的计数代码显示到我的标签文本中。这是我的代码，请告诉我如何解决这个问题。

ordering_and_billing.dBase dBase = new ordering_and_billing.dBase();
var mydbconnection = new dBase.dbconnection();

string sql = "SELECT * FROM `order` WHERE eventdate='" + lbldte.Text + "'";

MySqlCommand cmd = new MySqlCommand(sql, mydbconnection.Connection);
mydbconnection.Connection.Open();
MySqlDataReader rdr = cmd.ExecuteReader();
if (rdr.HasRows)
{
    while (rdr.Read())
    {
        Int32 count = (Int32)cmd.ExecuteScalar();
        string disp = count.ToString();
        lblcount.Text = disp;
    }
}

Answer 1

只需使用count函数:

string sql = "SELECT COUNT(*) FROM `order` WHERE eventdate='" + lbldte.Text + "'";

也不要使用 ExecuteReader，如果你想要一个像计数值这样的单个值，请使用 ExecuteScalar 函数:

lblcount.Text =cmd.ExecuteScalar().toString();