编译错误：当前范围内的重复声明

Question

我正在尝试从选定工作簿的多个工作表中收集数据。我正在使用以下代码：

Sub Multiplesheet()

Dim filepath As Variant
Dim outputFilePath As String
Dim outputSheetName As String
Dim sql As String
Dim wbk As Workbook, wks As Worksheet
Dim rng As Excel.Range
Dim sheetname As Variant

'To which file and sheet within the file should the output go?
outputFilePath = "C:\Users\z003k50s\Desktop\Test\Output.xlsx"
outputSheetName = "Sheet1"

For Each filepath In Application.GetOpenFilename(FileFilter:="Excel Files (*.xl*), *.xl*", MultiSelect:=True)
    Set schema = conn.OpenSchema(adSchemaTables)
    For Each sheetname In schema.GetRows(, , "TABLE_NAME") 'returns a 2D array of one column
        sql = sql & _
            "UNION ALL SELECT F1 " & _
            "FROM [" & sheetname & "]" & _
                "IN """ & filepath & """ ""Excel 12.0;"""
    Next
Next
sql = Mid(sql, 5) 'Gets rid of the UNION ALL from the first SQL

Dim conn As New ADODB.Connection
Dim rs As ADODB.Recordset
 With conn
    .Provider = "Microsoft.ACE.OLEDB.12.0"
    .ConnectionString = "Data Source=""" & filepath & """;" & _
        "Extended Properties=""Excel 12.0;HDR=No"""
    .Open
    Set rs = .Execute(sql)
    Set wbk = Workbooks.Open(outputFilePath, , True)
    Set wks = wbk.Sheets(outputSheetName)
    wks.Cells(2, 1).CopyFromRecordset rs
    wks.Columns.AutoFill
    .Close
End With

End Sub

当我调试时它会突出显示：

 conn As New ADODB.Connection

我是 Excel VBA 的新手，我不知道它是什么意思。

Answer 1

您的代码片段：

---

For Each filepath In Application.GetOpenFilename(FileFilter:="Excel Files (*.xl*), *.xl*", MultiSelect:=True)
'----------
    Set schema = conn.OpenSchema(adSchemaTables) '<~~~ HERE YOU HAVE USED 'conn'
'----------

    For Each sheetname In schema.GetRows(, , "TABLE_NAME") 'returns a 2D array of one column
        sql = sql & _
            "UNION ALL SELECT F1 " & _
            "FROM [" & sheetname & "]" & _
                "IN """ & filepath & """ ""Excel 12.0;"""
    Next
Next
sql = Mid(sql, 5) 'Gets rid of the UNION ALL from the first SQL

'---------
Dim conn As New ADODB.Connection '<~~~ already exists, so duplicate declaration
'---------

Dim rs As ADODB.Recordset
 With conn

从我的 cmets 中可以看出，您使用了 conn，然后尝试对其进行维度 (Dim)，这就是您收到编译错误的原因。