Question

是的，我已经看到this个问题。不，它没有解决我的问题。

我正在VB.Net中与SQL Server数据库连接的应用程序上工作。目前，我正在尝试让VB.Net应用程序在数据库上执行以下存储过程：

CREATE PROCEDURE dbo.AddSupplierAddress(
    @Supplier VARCHAR(100),
    @Street   VARCHAR(100),
    @City     VARCHAR(50),
    @Region   VARCHAR(50),
    @Code     VARCHAR(7),
    @Info     VARCHAR(500) = NULL,
    @response NVARCHAR(500) = OUTPUT
) AS
BEGIN
    DECLARE @SupplierID INT, @RegionID INT
    SELECT @SupplierID = supplier_id
      FROM suppliers
     WHERE supplier_name = @Supplier
    IF @SupplierID IS NULL
    BEGIN
        SET @response = 'Could not add address to Supplier "' + @Supplier + '".  Supplier does not exist.'
        RETURN
    END
    SELECT @RegionID = region_id
      FROM regions
     WHERE region_name = @Region
    IF @RegionID IS NULL
    BEGIN
        SET @response = 'Could not add address to Supplier "' + @Supplier + '". Region "' + @Region + '" does not exist.'
        RETURN
    END
    IF(EXISTS(SELECT supplier_id, street FROM supplier_addresses WHERE supplier_id = @SupplierID AND street = @Street))
    BEGIN
        SET @response = 'Could not add address to Supplier "' + @Supplier + '".  Address already exists in database.'
        RETURN
    END
    BEGIN TRANSACTION AddSuppAddr
    BEGIN TRY
        INSERT supplier_addresses(supplier_id, street, city, region_id, zip_code, notes)
        VALUES (@SupplierID, @Street, @City, @RegionID, @Code, @Info)
        COMMIT TRANSACTION AddSuppAddr
        SET @response = 'Success'
    END TRY
    BEGIN CATCH
        ROLLBACK TRANSACTION AddSuppAddr
        DECLARE @varErrorMessage NVARCHAR(4000), @varErrorSeverity INT, @varErrorState INT;
        SELECT @varErrorMessage = ERROR_MESSAGE(), @varErrorSeverity = ERROR_SEVERITY(), @varErrorState = ERROR_STATE();
        RAISERROR(@varErrorMessage, @varErrorSeverity, @varErrorState);
    END CATCH
END
GO

现在，我已使用以下命令在数据库本身上运行了此过程：

DECLARE @Resp NVARCHAR(500)
EXEC AddSupplierAddress 'Test Name', '123 main st.', 'Hamilton', 'Ontario', 'L84B5N', NULL, @Resp
PRINT @Resp

该程序运行正常。（我遇到的一个小问题是，在数据库上测试这些过程时，@Resp从未设置为我的输出值，但这是我不在此尝试解决的另一个问题）。在我的VB.Net程序中，我尝试使用以下代码运行此过程：

Private Sub CreateBtn_Click(sender As Object, e As EventArgs) Handles createBtn.Click
    If CreateSupplier(supplierTxt.Text, websiteTxt.Text, True) Then
        Dim message As String = ""
        If setAddress Then
            If AddSupplierAddress(supplierTxt.Text, streetTxt.Text, cityTxt.Text, regionTxt.Text, codeTxt.Text, infoTxt.Text, True) Then
                message = "Supplier and address have been added to the database."
            Else
                DeleteSupplier(supplierTxt.Text)
                Return
            End If
        Else
            message = "Supplier has been added to the database."
        End If
        If MessageBox.Show(message & vbCrLf & "Would you like to add any Contacts?", "Data Added", MessageBoxButtons.YesNo) = DialogResult.Yes Then
            Dim contact As New NewContactForm(supplierTxt.Text, False, True) With {
                .MdiParent = MdiParent
            }
            contact.Show()
        End If
    End If
End Sub

Public Function AddSupplierAddress(ByVal supplier As String,
                                   ByVal street As String,
                                   ByVal city As String,
                                   ByVal region As String,
                                   ByVal code As String,
                                   Optional info As String = "",
                                   Optional displayError As Boolean = False) As Boolean
    Dim errorMsg As String = ""
    Dim CMD As New SqlCommand("AddSupplierAddress")
    CMD.Parameters.Add("@Supplier", SqlDbType.VarChar).Value = supplier
    CMD.Parameters.Add("@Street", SqlDbType.VarChar).Value = street
    CMD.Parameters.Add("@City", SqlDbType.VarChar).Value = city
    CMD.Parameters.Add("@Region", SqlDbType.VarChar).Value = region
    CMD.Parameters.Add("@Code", SqlDbType.VarChar).Value = code
    If Not info.Equals("") Then CMD.Parameters.Add("@Info", SqlDbType.VarChar).Value = info
    If ExecuteCMDWithReturnValue(CMD, errorMsg) Then
        Return True
    Else
        If displayError Then
            MessageBox.Show(errorMsg, "Database Error")
            Return False
        Else
            Return False
        End If
    End If
End Function

Public Function ExecuteCMDWithReturnValue(ByRef CMD As SqlCommand, ByRef errorMessage As String) As Boolean
    Try
        OpenDBConnection()
        CMD.Parameters.Add("@response", SqlDbType.NVarChar, 500).Direction = ParameterDirection.Output
        CMD.Connection = DB_CONNECTION
        CMD.CommandType = CommandType.StoredProcedure
        CMD.ExecuteNonQuery()
        Dim result As String = CMD.Parameters("@response").Value
        If result.Equals("Success") Then
            ExecuteCMDWithReturnValue = True
        Else
            errorMessage = result
            ExecuteCMDWithReturnValue = False
        End If
    Catch ex As Exception
        Throw New Exception("Database Error: " & ex.Message)
        ExecuteCMDWithReturnValue = False
    Finally
        CloseDBConnection()
    End Try
End Function

现在，如上所述，当我在数据库上运行存储过程时，没有出现此错误。甚至更奇怪的是，我还有另一套程序被完全相同地编码，唯一的区别是supplier的每个实例都被customer取代，并且它们都可以正常工作！

我遇到的具体错误是标题，但您不必向上滚动它：

正式参数“ @response”未声明为OUTPUT参数，但实际参数已传递至请求的输出中。

什么可能导致我的问题？

Answer 1

恭喜，您遇到了令人讨厌的T-SQL陷阱。它默认允许不带引号的情况下指定字符串参数，这样

@response NVARCHAR(500) = OUTPUT

实际上等于

@response NVARCHAR(500) = 'OUTPUT'

当然，与将参数声明为输出参数不同，因为那是

@response NVARCHAR(500) OUTPUT

这特别糟糕，因为默认值只允许使用常量，而不能使用函数或表达式，而引号是可选的，则允许使用一些确实令人误解的声明：

@from DATETIME = GETDATE

仅当在未指定@from的值的情况下调用该过程时，此方法才会失败：此时，字符串'GETDATE'将被转换为DATETIME（这当然会失败）

正式参数““ @response””未声明为OUTPUT参数，但实际参数已传递至请求的输出

1 个答案: