Question

我有Amount的文本框，我希望以下语句来显示它。

以下是我的代码：

<!--Amount-->
    <div class="form-group">
        <label class="control-label col-lg-4">
            Amount</label>
        <div class="col-lg-8">
            <asp:TextBox ID="txtBudget" runat="server" class="form-control" AutoPostBack="True" />
        </div>
    </div>

代码背后：

 void GetTotalAmount()
{
    con.Open();
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = con;
    cmd.CommandText = "SELECT SUM(Materials.SellingPrice + Equipments.Price + Resource_Vehicles.Cost + Contractors.Rate) " +
    "FROM ProjectTasks INNER JOIN Resource_Contractors ON ProjectTasks.TaskID = Resource_Contractors.TaskID INNER JOIN " +
    "Resource_Equipments ON ProjectTasks.TaskID = Resource_Equipments.TaskID INNER JOIN Resource_Materials ON ProjectTasks.TaskID = Resource_Materials.TaskID INNER JOIN " +
    "Resource_Vehicles ON ProjectTasks.TaskID = Resource_Vehicles.TaskID INNER JOIN Contractors ON Resource_Contractors.ContractorID = Contractors.ContractorID INNER JOIN " +
    "Materials ON Resource_Materials.MaterialID = Materials.MaterialID INNER JOIN Equipments ON Resource_Equipments.EquipmentID = Equipments.EquipmentID INNER JOIN " +
    "Vehicles ON Resource_Vehicles.VehicleID = Vehicles.VehicleID WHERE ProjectTasks.TaskID=@TaskID";
    SqlDataReader dr = cmd.ExecuteReader();
    con.Close();
    }

谢谢！

Answer 1

如果您的查询非常简单，只需使用ExecuteScalar获取此值并指定文本框的Text属性即可。您不需要使用ExecuteReader。

var sum = cmd.ExecuteScalar();
txtBudget.Text = sum.ToString();

还可以使用using statement来处理您的连接和命令，如;

void GetTotalAmount()
{
    using(var con = new SqlConnection(conString))
    using(var cmd = con.CreateCommand())
    {
       cmd.CommandText = "...";
       con.Open();
       var sum = cmd.ExecuteScalar();
       txtBudget.Text = sum.ToString();
    }
}

Answer 2

您只需使用SqlDataReader.GetDouble：

using (var dr = cmd.ExecuteReader()) // use using for everything implementing IDisposable, also connection
{
    if (dr.HasRows)
    {
        dr.Read(); // advances reader to first record
        txtBudget.Text = dr.GetDouble(0).ToString();
    }
}

如果您只选择一个值（如Soner所示），则另一种方法是使用ExecuteScalar。

如何在文本框中显示总金额？

2 个答案: