Import from closed workbooks using ADODB - excel

Question

After so many hours in that field, I could be able to get data from all the worksheets in closed workbook and could get data from specific columns using ADODB.
#Siddharth Rout helped me to be able to get the sheet names in the order of tab.
The following code works fine for only one closed workbook. But in fact I am trying to do the same and get all the data from the specific column (Reference - Ref No - Number ..) from several workbooks
Sub ImportFromClosedWorkbook()
Dim e, ws As Worksheet, cn As ADODB.Connection, rs As ADODB.Recordset, rsHeaders As ADODB.Recordset, b As Boolean, sFile As String, shName As String, strSQL As String, iCol As Long
sFile = ThisWorkbook.Path & "\Sample.xlsx"
Dim con As Object
Set con = CreateObject("DAO.DBEngine.120")
Dim rsData As ADODB.Recordset
Set cn = New ADODB.Connection
cn.Open ConnectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source='" & sFile & "';" & "Extended Properties=""Excel 12.0;HDR=YES;IMEX=1;"";"
Set ws = ThisWorkbook.ActiveSheet
Dim db As Object, i As Long
Set db = con.OpenDatabase(sFile, False, True, "Excel 12.0 XMl;")
For i = 0 To db.TableDefs.Count - 1
sName = db.TableDefs(i).Name
b = False
strSQL = "SELECT * FROM [" & sName & "]"
Set rsHeaders = New ADODB.Recordset
rsHeaders.Open Source:=strSQL, ActiveConnection:=cn, Options:=1
For iCol = 0 To rsHeaders.Fields.Count - 1
For Each e In Array("Ref No", "Reference", "Number")
If e = rsHeaders.Fields(iCol).Name Then
b = True: Exit For
End If
Next e
If b Then Exit For
Next iCol
If b Then
strSQL = "SELECT [" & e & "] FROM [" & sName & "]"
Set rsData = New ADODB.Recordset
Set rsData = cn.Execute(strSQL)
ws.Range("A" & ws.Cells(Rows.Count, 1).End(xlUp).Row + 1).CopyFromRecordset rsData
rsData.Close
End If
Next i
db.Close: Set db = Nothing
Set con = Nothing
cn.Close: Set cn = Nothing
End Sub
Is it suitable to build a public procedure or what's the best approach in that case and how can I release the objects in correct way?

Answer 1

I would break out your code even more - there are distinct activities which could be factored out into reusable methods.
FYI your tableDefs objects already contains the field names, so there's no need to separately query for those.
Eg:
Sub ImportFromClosedWorkbook()
Dim sFile As String, sheetName As String, colName As String, rs As ADODB.Recordset
Dim cols As Collection, col
sFile = ThisWorkbook.FullName
Set cols = FindColumns(sFile, Array("Ref", "Reference", "RefNo"))
'loop found columns
For Each col In cols
sheetName = col(0)
colName = col(1)
Debug.Print "##", sheetName, colName
Set rs = WorkBookQuery(sFile, "Select [" & colName & "] from [" & sheetName & "]")
If Not rs.EOF Then
' ActiveSheet.Cells(Rows.Count, "A").End(xlUp).CopyFromRecordset rs
End If
Next col
End Sub
'given a workbook path, find all column headings matching andname in arrNames
'returns a collections of [sheetName, columnName] arrays
Function FindColumns(wbFullPath As String, arrNames) As Collection
Dim tabledefs As Object, td As Object, f As Object, rv As New Collection
Set tabledefs = CreateObject("DAO.DBEngine.120") _
.OpenDatabase(wbFullPath, False, True, "Excel 12.0 XMl;").tabledefs
For Each td In tabledefs
For Each f In td.Fields
'Debug.Print td.Name, f.Name
If Not IsError(Application.Match(f.Name, arrNames, 0)) Then
rv.Add Array(td.Name, f.Name)
End If
Next f
Next td
Set FindColumns = rv
End Function
'run a SQL query against a workbook
Function WorkBookQuery(wbFullPath As String, SQL As String) As ADODB.Recordset
Dim rs As ADODB.Recordset
With New ADODB.Connection
.Open "Provider=Microsoft.ACE.OLEDB.12.0;Data Source='" & wbFullPath & "';" & _
"Extended Properties=""Excel 12.0;HDR=YES;IMEX=1;"";"
Set WorkBookQuery = .Execute(SQL, Options:=1)
End With
End Function

Answer 2

There seems to be a logical error in the process of cycling through the fields. It would be nice to use a user-defined function that checks if the field name exists.
Sub ImportFromClosedWorkbook()
Dim e, ws As Worksheet, cn As ADODB.Connection, rs As ADODB.Recordset, rsHeaders As ADODB.Recordset, b As Boolean, sFile As String, shName As String, strSQL As String, iCol As Long
Dim sField As String
sFile = ThisWorkbook.Path & "\Sample.xlsx"
Dim con As Object
Set con = CreateObject("DAO.DBEngine.120")
Dim rsData As ADODB.Recordset
Set cn = New ADODB.Connection
cn.Open ConnectionString:="Provider=Microsoft.ACE.OLEDB.12.0;Data Source='" & sFile & "';" & "Extended Properties=""Excel 12.0;HDR=YES;IMEX=1;"";"
Set ws = ThisWorkbook.ActiveSheet
Dim db As Object, i As Long
Set db = con.OpenDatabase(sFile, False, True, "Excel 12.0 XMl;")
For i = 0 To db.TableDefs.Count - 1
sName = db.TableDefs(i).Name
b = False
strSQL = "SELECT * FROM [" & sName & "]"
Set rsHeaders = New ADODB.Recordset
rsHeaders.Open Source:=strSQL, ActiveConnection:=cn, Options:=1
For iCol = 0 To rsHeaders.Fields.Count - 1
' For Each e In Array("Ref No", "Reference", "Number")
' If e = rsHeaders.Fields(iCol).Name Then
' b = True: Exit For
' End If
' Next e
' If b Then Exit For
' Next iCol
' If b Then
sField = rsHeaders.Fields(iCol).Name
If isField(sField) Then
strSQL = "SELECT [" & sField & "] FROM [" & sName & "]"
Set rsData = New ADODB.Recordset
Set rsData = cn.Execute(strSQL)
ws.Range("A" & ws.Cells(Rows.Count, 1).End(xlUp).Row + 1).CopyFromRecordset rsData
rsData.Close
End If
Next iCol
Next i
db.Close: Set db = Nothing
Set con = Nothing
cn.Close: Set cn = Nothing
End Sub
Function isField(sField As String) As Boolean
Dim vName As Variant, e As Variant
vName = Array("Ref No", "Reference", "Number")
For Each e In vName
If e = sField Then
isField = True
Exit Function
End If
Next e
End Function

Answer 3

If all the files have the same structure and are in a folder, you could use the FileSystemObject reference as below:
"https://stackoverflow.com/questions/10380312/loop-through-files-in-a-folder-using-vba"
and you could run the existing code in a loop in the file system code, hope that works