在SQL Server查詢的標簽中顯示值

Question

我正在嘗試從SQL查詢加載要標記的值：

sc.Open();
string type = Vehicle_cost.SelectedText;
string query = ("select Type from Vehicle_Registor where Reg_No = '" + type + "';");

SqlCommand cmd1 = new SqlCommand(query, sc);
SqlDataReader sdr = cmd1.ExecuteReader();
label23.Text = sdr.ToString();
sc.Close();

Answer 1

嘗試下面的代碼。

sc.Open();

string query = @"select Type from Vehicle_Registor where Reg_No = @Reg_No";

SqlCommand cmd1 = new SqlCommand(query, sc);
cmd1.Parameters.AddWithValue("@Reg_No", Vehicle_cost.SelectedText);

SqlDataReader sdr = cmd1.ExecuteReader();
sdr.Read();

label23.Text = sdr[0].ToString();

sc.Close();

Answer 2

嘗試這樣的事情：

SqlCommand cmd1 = new SqlCommand(query, sc);
using (SqlDataReader sdr = cmd1.ExecuteReader())
{
    while (sdr.Read())
    {
        for (int i = 0; i < sdr.FieldCount; i++)
        {
            label23.text += sdr[i].ToString();
        }
    }
}
sc.Close();