Visual Basic循环查询结果

Question

我想要一个循环查询结果并将它们显示在Visual Basic的列表框中的代码。到目前为止我所拥有的是一个存储过程，一个列表框和一个按钮。

存储过程IM调用被称为“CycleCustomers”和在SQL如下：

ALTER PROCEDURE CycleCustomers 
-- Add the parameters for the stored procedure here 
@p1 int 

    AS 
    BEGIN 
-- SET NOCOUNT ON added to prevent extra result sets from 
-- interfering with SELECT statements. 
SET NOCOUNT ON; 

-- Insert statements for procedure here 
SELECT FirstName from tblCustomer where CustomerId = @p1 
END 

上按一下按钮的代码，我有如下

Dim dc = New DataTestDataContext 
    Dim DealerCount As Int32 
    DealerCount = 0 
    ListBox2.Items.Clear() 

    Do Until DealerCount = 10 
     dc.CycleCustomers(DealerCount) 
     ListBox2.Items.Add(dc.CycleCustomers(DealerCount).ReturnValue) 
     DealerCount = DealerCount + 1 
    Loop 

当按钮被点击，我的列表框返回10个零。我究竟做错了什么？提前致谢。

编辑：这里是CYCLECUSTOMERS功能

<FunctionAttribute(Name:="dbo.CycleCustomers")> _ 
Public Function CycleCustomers(<Parameter(DbType:="Int")> ByVal p1 As System.Nullable(Of Integer)) As ISingleResult(Of CycleCustomersResult1) 
    Dim result As IExecuteResult = Me.ExecuteMethodCall(Me, CType(MethodInfo.GetCurrentMethod,MethodInfo), p1) 
    Return CType(result.ReturnValue,ISingleResult(Of CycleCustomersResult1)) 
End Function 

Answer 1

看一看这里：http://msdn.microsoft.com/en-us/library/bb534556(v=vs.110).aspx

你所取回的类型是CycleCustomerResult1，这是一个IEnumerable的ISingleResult。你应该能够使用LINQ做的是一样的东西：

Dim dc = New DataTestDataContext 
Dim DealerCount As Int32 
DealerCount = 0 
ListBox2.Items.Clear() 

Do Until DealerCount = 10 
    Dim Customer = dc.CycleCustomers(DealerCount).SingleOrDefault() 

    If (Not(Customer Is Nothing)) 
    ListBox2.Items.Add(Customer.FirstName) 
    End If 

    DealerCount = DealerCount + 1 

Loop 

我没有Visual Studio中的时刻进行检查：还我一般使用C＃，所以我的VB的精度可能是穷人。

但是，无论如何，你采取的方法似乎非常非正统。理想情况下，您将有一个存储过程返回一组行，然后遍历该结果，并添加到列表框中。

因此，例如，一个存储过程是这样的：

ALTER PROCEDURE CycleCustomers 
    AS 
    BEGIN 
-- SET NOCOUNT ON added to prevent extra result sets from 
-- interfering with SELECT statements. 
SET NOCOUNT ON; 

-- Insert statements for procedure here 
SELECT FirstName from tblCustomer 
END 

那么功能更喜欢这个

Dim Customers = dc.CycleCustomers() 

For Each Customer In Customers 
    ListBox2.Items.Add(Customer.FirstName) 
Next 

Answer 2

好吧，我做到了通过LINQ to SQL和存储过程，但现在的工作。下面是按钮

Dim number As Int32 
    number = 1 
    Dim dc = New DataTestDataContext 

    Do Until number > dc.MaxCustomerId.First.CustomerId 
     Dim Customers = From cust In dc.CycleCustomers(number) _ 
         Where cust.CustomerId = number _ 
         Select cust 

     For Each cust In Customers 
      ListBox2.Items.Add(cust.FirstName) 

     Next 
     number = number + 1 
    Loop 

代码这里是存储过程的代码

ALTER PROCEDURE CycleCustomers 
-- Add the parameters for the stored procedure here 
@p1 int 

    AS 
    BEGIN 
-- SET NOCOUNT ON added to prevent extra result sets from 
-- interfering with SELECT statements. 
SET NOCOUNT ON; 

-- Insert statements for procedure here 
SELECT CustomerId, FirstName from tblCustomer where CustomerId = @p1 
END 

我做了另一个存储过程的循环，它选择最大的ID号，它的代码是在这里

ALTER PROCEDURE MaxCustomerId 

AS 
BEGIN 
-- SET NOCOUNT ON added to prevent extra result sets from 
-- interfering with SELECT statements. 
SET NOCOUNT ON; 

    SELECT CustomerId 
    FROM tblCustomer 
WHERE CustomerId=(SELECT max(CustomerId) FROM tblCustomer) 

END