通过传递两个日期参数来查询调度表

Question

我需要通过say来查看订单详细信息;每周，每月订单通过传递两个日期参数。我尝试了几次，但它返回null。

这是我到目前为止的代码：

SELECT A.Dispatch_ID, 
A.Dispatched_Date, 
A.Product_ID, 
A.Product_Code, 
A.Product_Loaded, 
A.Meter_Ticket_ID, 
A.Marketer_ID, 
A.Dispatched_Truck, 
A.Loaded_Quantity, 
A.Loading_Depot, 
A.Over_Loaded, 
A.Under_Loaded, 
A.User_Name, 
A.Employee_ID, 
B.Dispatched_Date AS Dispatched_Date1 
FROM ((SELECT Dispatch_ID, Format(Dispatched_Date, 'dd/mm/yyyy') AS Dispatched_Date, Product_ID, Product_Code, Product_Loaded, Meter_Ticket_ID, Marketer_ID, Dispatched_Truck, Loaded_Quantity, Loading_Depot, Over_Loaded, Under_Loaded, User_Name, Employee_ID FROM Dispatched_Entry) A 
INNER JOIN (SELECT Dispatch_ID, Format(Dispatched_Date, 'dd/mm/yyyy') AS Dispatched_Date, Product_ID, Product_Code, Product_Loaded, Meter_Ticket_ID, Marketer_ID, Dispatched_Truck, Loaded_Quantity, Loading_Depot, Over_Loaded, Under_Loaded, User_Name, Employee_ID FROM Dispatched_Entry Dispatched_Entry_1)B ON A.Product_ID = B.Product_ID) 
WHERE A.Dispatched_Date =? AND B.Dispatched_Date =? 

任何帮助将不胜感激。

Answer 1

如果要通过SqlCommand实例将参数传递到SQL查询中，请使用命名参数。下面是在C＃中最原始的例子：

var query = @"SELECT A.Dispatch_ID, 
       ... 
       WHERE A.Dispatched_Date = @dateA AND B.Dispatched_Date = @dateB"; 
var connection = new SqlConnection(connectionString); 
var command = new SqlCommand(query, connection); 
command.Parameters.AddWithValue("@dateA", someDateA); 
command.Parameters.AddWithValue("@dateB", someDateB); 

上有MSDN进一步的例子。

---

要配置直接SqlDataSource在ASP.NET中，类似这样的：

<asp:dropdownlist 
    id="DropDownListA" 
    runat="server" 
    autopostback="True"> 
    ... 
</asp:dropdownlist> 

<asp:dropdownlist 
    id="DropDownListB" 
    runat="server" 
    autopostback="True"> 
    ... 
</asp:dropdownlist> 

<asp:sqldatasource 
    id="SqlDataSource1" 
    runat="server" 
    connectionstring="<%$ ConnectionStrings:MyConnectionString %>" 
    selectcommand="SELECT A.Dispatch_ID, 
        ... 
        WHERE A.Dispatched_Date = @dateA AND B.Dispatched_Date = @dateB"> 
    <selectparameters> 
     <asp:controlparameter name="dateA" controlid="DropDownListA" propertyname="SelectedValue"/> 
     <asp:controlparameter name="dateB" controlid="DropDownListB" propertyname="SelectedValue"/> 
    </selectparameters> 
</asp:sqldatasource> 

更多信息，请MSDN找到。