通过.Net客户端的OleDB引用的Excel值
我试图通过OleDB读取Excel文件（.xls，我认为Excel 2003兼容），但它无法获取引用字段的值。
这是我目前的testing代码（请注意，这只是该课程的一部分）：
Private m_conn As OleDbConnection Public Sub New(ByVal fileName As String) Dim connString As String = String.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=Excel 8.0;", fileName) m_conn = New OleDbConnection(connString) m_conn.Open() End Sub Public Sub GetSheet(ByVal sheet As String) Dim query As String = String.Format("SELECT * FROM [{0}]", sheet) Using cmd As OleDbCommand = m_conn.CreateCommand() cmd.CommandText = query Dim ds As New DataSet() Dim a As New OleDbDataAdapter(cmd) Using rdr As OleDbDataReader = cmd.ExecuteReader() While rdr.Read() Debug.WriteLine(rdr.Item(0).ToString()) End While End Using End Using End Sub 但是如果这个值是一个引用（类似于=+'MySheetName'!K37 ），我只是从调用rdr.Item（0）得到一个DBNull。
我可以通过自动化Excel来解决此问题，但是不希望使用Excel自动化，所以想知道是否有人知道如何去做。
不涉及全class，但你会得到这个想法。 这不是excel自动化，而是Microsoft Access oledb驱动读取excel文件，所以它的速度要快得多。
你必须有正确的registry设置，并确定你阅读哪个版本的Excel，你必须安装一些驱动程序。 注意：Office 2010驱动程序可以从Microsoft下载，但我不确定他们是否也安装了MS Office文件的旧版本所需的驱动程序，也就是说，我只在我的SQL服务器上安装了MS Office的旧版oledb驱动程序加载。
'''<summary> ''' Retrieved the data in spreadsheet to a ADO.net dataset. This should make things mega easy to work with. ''' See Microsoft KB316934 for details on how this was done. ''' Optional First row = field titles method variable, which extends the options available to the calling application. '''</summary> '''<example> ''' When passing in the variable "SheetorNamedRangeorSheetNumber" please use the following examples. '''• Use the sheet name followed by a dollar sign (for example, [Sheet1$] or [My Worksheet$]). A workbook table that is referenced in this manner includes the whole used range of the worksheet. '''Select * from [Sheet1$] '''• Use a range with a defined name (for example, [MyNamedRange]): '''Select * from [MyNamedRange] '''• Use a range with a specific address (for example, [Sheet1$A1:B10]): '''Select * from [Sheet1$A1:B10] '''</example> ''' <param name="filePath">The full path to the excel file. If you pass in a relative path, it will be automatically converted to a full path. The file has to exist for this method to return a dataset. If the file doesn't exist a FileNotFoundException will be raised.</param> ''' <param name="firstRowTitles">Boolean to indicate if the first row of the spreadsheet contains column titles.</param> ''' <param name="readAsTextData">Boolean to indicate if the spreadsheet should be read as as text data. This is particularly important for columns that may contain mixed numberic and alpha numeric data. </param> ''' <remarks> ''' Its not possible to open and excel workbook via this method if there is password protection on the workbook. It could be removed ''' by automation and then loaded or manaully removed before running this code. ''' ''' LL: The IMEX=1 setting then references the values set in the Windows registry ''' ''' Check the following registry settings for the *machine*: ''' Hkey_Local_Machine/Software/Microsoft/Jet/4.0/Engines/Excel/TypeGuessRows ''' Hkey_Local_Machine/Software/Microsoft/Jet/4.0/Engines/Excel/ImportMixedTypes ''' Hkey_Local_Machine/SOFTWARE/Wow6432Node/Microsoft/Jet/4.0/Engines/Excel ''' TypeGuessRows: setting the value to 0 (zero) will force ADO to scan ''' all column values before choosing the appropriate data type. ''' ImportMixedTypes: should be set to value 'Text' ie import mixed-type ''' columns as text: ''' Using IMEX=1 in the connection string (as you have done) ensures the ''' registry setting is applied. ''' Office 2007 data drivers can be downloaded free at <see>http://www.microsoft.com/downloads/details.aspx?familyid=7554F536-8C28-4598-9B72-EF94E038C891&displaylang=en</see> ''' ''' </remarks> Overloads Function GetDataSet(ByVal filePath As String, ByVal sheetOrNamedRangeOrSheetNumber As String, ByVal firstRowTitles As Boolean, ByVal readAsTextData As Boolean) As System.Data.DataSet Dim strConnectionString As String = String.Empty Dim connection As New System.Data.OleDb.OleDbConnection Dim cmd As New System.Data.OleDb.OleDbCommand Dim adp As New System.Data.OleDb.OleDbDataAdapter Dim dset As New System.Data.DataSet Dim strSheetName As String Dim ExcelFileInfo As System.IO.FileInfo ' Registry manipulation features. Dim currentJetRegistryValue As String = "19" ' Excel file extension handling Dim ExcelFileType As Excel.ExcelVersion = ExcelVersion.Unknown ExcelFileInfo = New System.IO.FileInfo(filePath) If ExcelFileInfo.Exists Then Select Case ExcelFileInfo.Extension.ToLower Case ".xls" ExcelFileType = ExcelVersion.Excel97_2003 Case ".xlsx" ExcelFileType = ExcelVersion.Excel2007 Case Else ExcelFileType = ExcelVersion.Unknown Throw New ExcelException(-2, String.Format("Excel file extension '{0}' is not valid or code changes are required to handle that file extension.", ExcelFileInfo.Extension), "") End Select Try Select Case ExcelFileType Case ExcelVersion.Excel97_2003 ' Need to get the current registry setting, because we can change the value temporarily currentJetRegistryValue = Me.GetJetExcelRegistry If currentJetRegistryValue <> "0" Then Me.UpdateJetExcelRegistry("0") End If If readAsTextData Then If firstRowTitles Then strConnectionString = System.String.Format(My.Resources.ExcelConnectionWithHeaderAllText, ExcelFileInfo.FullName) Else strConnectionString = System.String.Format(My.Resources.ExcelConnectionWithoutHeaderAllText, ExcelFileInfo.FullName) End If Else If firstRowTitles Then strConnectionString = System.String.Format(My.Resources.ExcelConnectionWithHeader, ExcelFileInfo.FullName) Else strConnectionString = System.String.Format(My.Resources.ExcelConnectionWithoutHeader, ExcelFileInfo.FullName) End If End If Case ExcelVersion.Excel2007 ' Need to get the current registry setting, because we can change the value temporarily currentJetRegistryValue = Me.GetExcel2007Registry If currentJetRegistryValue <> "0" Then Me.UpdateExcel2007Registry("0") End If If firstRowTitles Then strConnectionString = System.String.Format(My.Resources.Excel2007ConnectionWithHeaderAllText, ExcelFileInfo.FullName) Else strConnectionString = System.String.Format(My.Resources.Excel2007ConnectionWithoutHeaderAllText, ExcelFileInfo.FullName) End If End Select If strConnectionString = String.Empty Then Throw New ExcelException(-3, "Excel Connection string hasn't been set.", "") End If connection = New System.Data.OleDb.OleDbConnection With connection .ConnectionString = strConnectionString .Open() End With ' Create a command connection cmd = New System.Data.OleDb.OleDbCommand With cmd .Connection = connection .CommandType = CommandType.Text If IsNumeric(sheetOrNamedRangeOrSheetNumber) = True Then ' Ok extract the sheet name from the connection first Dim objDT As New System.Data.DataTable objDT = connection.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, New Object() {Nothing, Nothing, Nothing, "TABLE"}) strSheetName = objDT.Rows(CInt(sheetOrNamedRangeOrSheetNumber)).Item("TABLE_NAME").ToString objDT = Nothing .CommandText = System.String.Format(System.Globalization.CultureInfo.InvariantCulture, My.Resources.ExcelSelectStatement, strSheetName) Else ' Must be a name, range or name Cell reference .CommandText = System.String.Format(System.Globalization.CultureInfo.InvariantCulture, My.Resources.ExcelSelectStatement, sheetOrNamedRangeOrSheetNumber) End If '.ExecuteReader() 'Forward only Dataset End With ' Create a data adapter to store the inforamtion adp = New System.Data.OleDb.OleDbDataAdapter dset = New DataSet With adp .SelectCommand = cmd .Fill(dset, My.Resources.DataSetTableName) End With Select Case ExcelFileType Case ExcelVersion.Excel97_2003 ' Restore the Excel readrows value, as we have finished with our modification. If currentJetRegistryValue <> Me.GetJetExcelRegistry Then ' Restore the registry setting (Securtiy implications) Me.UpdateJetExcelRegistry(currentJetRegistryValue) End If Case ExcelVersion.Excel2007 ' Restore the Excel readrows value, as we have finished with our modification. If currentJetRegistryValue <> Me.GetExcel2007Registry Then ' Restore the registry setting (Securtiy implications) Me.UpdateExcel2007Registry(currentJetRegistryValue) End If End Select ' Return the resulting dataset to the calling application GetDataSet = dset Catch comex As System.Runtime.InteropServices.COMException Throw New ExcelException(comex.ErrorCode, comex.Message, comex.InnerException) Catch ex As System.InvalidOperationException Throw New ExcelException(-1, ex.Message, ex.InnerException) Finally If Not cmd Is Nothing Then cmd = Nothing If Not connection Is Nothing Then connection.Close() connection.Dispose() connection = Nothing End If If Not adp Is Nothing Then adp = Nothing If Not dset Is Nothing Then dset = Nothing End Try Else Throw New System.IO.FileNotFoundException(System.String.Format(System.Globalization.CultureInfo.InvariantCulture, My.Resources.FileNotFound, filePath)) Return Nothing End If End Function
项目资源：
Excel2007ConnectionWithHeader提供程序= Microsoft.ACE.OLEDB.12.0;数据源= {0};扩展属性=“Excel 12.0; HDR =是”; Excel2007ConnectionWithHeaderAllText提供程序= Microsoft.ACE.OLEDB.12.0;数据源= {0};扩展属性=“Excel 12.0; HDR =是; IMEX = 1”;
Excel2007ConnectionWithoutHeader提供程序= Microsoft.ACE.OLEDB.12.0;数据源= {0};扩展属性=“Excel 12.0; HDR =否”;
Excel2007ConnectionWithoutHeaderAllText提供程序= Microsoft.ACE.OLEDB.12.0;数据源= {0};扩展属性=“Excel 12.0; HDR =否; IMEX = 1”;
ExcelAutomationError未知Excel自动化错误“{0}”：{1}。 {2}
ExcelConnectionWithHeader提供程序= Microsoft.Jet.OLEDB.4.0;数据源= {0};扩展属性=“Excel 8.0; HDR =是”;
ExcelConnectionWithHeaderAllText提供程序= Microsoft.Jet.OLEDB.4.0;数据源= {0};扩展属性=“Excel 8.0; HDR =是; IMEX = 1”;
ExcelConnectionWithoutHeader提供程序= Microsoft.Jet.OLEDB.4.0;数据源= {0};扩展属性=“Excel 8.0; HDR =否”;
ExcelConnectionWithoutHeaderAllText提供程序= Microsoft.Jet.OLEDB.4.0;数据源= {0};扩展属性=“Excel 8.0; HDR =否; IMEX = 1”; ExcelException“读取excel数据文件”{0}“时出错消息：{1}”
ExcelOledbException“Oledb错误读取excel数据文件'{0}'。消息：{1}”
ExcelPasswordException无法解密安全的Excel文件。
ExcelPasswordRestriction Excel中包含一个密码，可以限制读取工作簿。 请从“{0}”中删除工作簿密码。 然后重试。
ExcelSelectStatement SELECT * FROM [{0}]