我可以使用参数化查询从 SQL Server VarBinary 列返回字节数组吗？

我编写了一个小型 VBA 过程来测试使用 ADO 将文件作为二进制数据上传到 SQL Server 中的 VarBinary 列以及从中下载文件。上传过程似乎可以正常工作，但我无法让下载过程正常工作。

我相信 VarBinary 的输出参数设置不正确，但我找不到任何有关如何正确设置的文档。

我收到运行时错误 3708“参数对象定义不正确。提供的信息不一致或不完整。”在线.Parameters.Append .CreateParameter("@myblob", adVarBinary, adParamOutput)

Update: SELECT ? = myblob FROM bin_table WHERE ID = ?;似乎返回一个二进制字符串，而不是二进制数组。我相信这就是问题所在，但我仍然不知道如何解决它。

Update：我通过添加修复了编译错误“类型不匹配：需要数组或用户定义的类型”.Value到行尾WriteFile "C:\some_new_file.pdf", .Parameters("@myblob").

任何帮助是极大的赞赏。谢谢！

Private Sub TestReadWriteBlob()

    Dim objConnection As New ADODB.Connection
    Dim objCommand As New ADODB.Command
    Dim objRecordset As New ADODB.Recordset
    Dim intNewID As Integer

    With objConnection
        .CursorLocation = adUseClient
        .ConnectionString = "PROVIDER=SQLOLEDB;Server=<server>;Database=<database>;UID=<uid>;PWD=<pwd>;trusted_connection=false;"
        .Open
    End With

    With objCommand
        .ActiveConnection = objConnection
        .CommandText = "INSERT INTO bin_table ( myblob ) VALUES ( ? ); SELECT ? = id FROM bin_table WHERE ID = @@IDENTITY;"
        .CommandType = adCmdText
        .Parameters.Append .CreateParameter("@myblob", adVarBinary, adParamInput, -1, ReadFile("C:\some_file.pdf"))
        .Parameters.Append .CreateParameter("@NewID", adInteger, adParamOutput)
        .Execute
        intNewID = .Parameters("@NewID")
    End With

    Debug.Print intNewID

    Set objCommand = Nothing
    With objCommand
        .ActiveConnection = objConnection
        .CommandText = "SELECT ? = myblob FROM bin_table WHERE ID = ?;"
        .CommandType = adCmdText
        .Parameters.Append .CreateParameter("@myblob", adVarBinary, adParamOutput)
        .Parameters.Append .CreateParameter("@NewID", adInteger, adParamInput, , intNewID)
        .Execute
        WriteFile "C:\some_new_file.pdf", .Parameters("@myblob").Value
    End With

End Sub

Public Function ReadFile(ByVal strPath As String) As Byte()

    Dim intFile As Integer

    intFile = FreeFile
    Open strPath For Binary Access Read As intFile
    ReDim ReadFile(LOF(intFile) - 1)
    Get intFile, , ReadFile
    Close intFile

End Function

Public Sub WriteFile(ByVal strPath As String, bytBlob() As Byte, Optional ByVal Overwrite As Boolean = True)

    Dim intFile As Integer

    intFile = FreeFile
    If Overwrite And Dir(strPath) <> "" Then
        Kill strPath
    End If
    Open strPath For Binary Access Write As intFile
    Put intFile, , bytBlob
    Close intFile

End Sub

我找不到任何方法使用参数从 SQL Server 中的 VarBinary 列返回字节数组。然而，我确实发现从记录集中做到这一点是可行的。附加的代码可以完成这项工作。

我仍在寻找一种使用参数返回字节数组的方法，并且会在几天内坚持接受答案，以防有人有解决方案。

Private Sub TestReadWriteBlob()

    Dim objConnection As New ADODB.Connection
    Dim objCommand As New ADODB.Command
    Dim intNewID As Integer

    With objConnection
        .CursorLocation = adUseClient
        .ConnectionString = "PROVIDER=SQLOLEDB;Server=<server>;Database=<database>;UID=<uid>;PWD=<pwd>;trusted_connection=false;"
        .Open
    End With

    With objCommand
        .ActiveConnection = objConnection
        .CommandText = "INSERT INTO bin_table ( myblob ) VALUES ( ? ); SELECT ? = id FROM bin_table WHERE ID = @@IDENTITY;"
        .CommandType = adCmdText
        .Parameters.Append .CreateParameter("@myblob", adVarBinary, adParamInput, -1, ReadFile("C:\Users\Thomas\Desktop\some_file.pdf"))
        .Parameters.Append .CreateParameter("@NewID", adInteger, adParamOutput)
        .Execute
        intNewID = .Parameters("@NewID")
    End With

    Set objCommand = Nothing
    With objCommand
        .ActiveConnection = objConnection
        .CommandText = "SELECT myblob FROM bin_table WHERE ID = ?;"
        .CommandType = adCmdText
        .Parameters.Append .CreateParameter("@NewID", adInteger, adParamInput, , intNewID)
        WriteFile "C:\Users\Thomas\Desktop\blob\some_file.pdf", .Execute.Fields("myblob").Value
    End With

End Sub

Public Function ReadFile(ByVal strPath As String) As Byte()

    Dim intFile As Integer

    intFile = FreeFile
    Open strPath For Binary Access Read As intFile
    ReDim ReadFile(LOF(intFile) - 1)
    Get intFile, , ReadFile
    Close intFile

End Function

Public Sub WriteFile(ByVal strPath As String, bytBlob() As Byte, Optional ByVal Overwrite As Boolean = True)

    Dim intFile As Integer

    intFile = FreeFile
    If Overwrite And Dir(strPath) <> "" Then
        Kill strPath
    End If
    Open strPath For Binary Access Write As intFile
    Put intFile, , bytBlob
    Close intFile

End Sub