Merging two spreadsheets after a button click - vba

Question

I have 2 spreadsheets:
main.xlsxm
drs.xlsx
I am trying to merge the two spreadsheets - this event will be launched after a button click on the main.xlsx spreadsheet (so the VBA code will reside on main.xlsx).
But I'm having difficulty writing my code, I originally tried using a variation of the following Excel formula but it was incredibly slow.
=IFERROR(INDEX([1.xlsx]Sheet1!$A:$A,SMALL(IF([1.xlsx]Sheet1!$B:$B=$A2,ROW([1.xlsx]Sheet1!$B:$B),99^99),COLUMN(A$1))),"")
I am trying to accomplish the following in VBA:
If column value E in drs.xlsx equals column value A in main.xlsx:
Then on the matching row in main.xlsx
Copy column value B in drs.xls to column value J in main.xlsx
If a second match is found (provided it is not the same as the first match):
Where column value E in drs.xlsx equals column value A in main.xlsx
Copy column value B in drs.xls to column value K in main.xlsx
If a third match is found (provided it is not the same as the first and second match):
Where column value E in drs.xlsx equals column value A in main.xlsx
Copy column value B in drs.xls to column value L in main.xlsx
If it happens for a fourth time then ignore…
How would I articulate this as VBA code?
This is my code so far (which prepares the spreadsheet ready):
Sub DRS_Update()
Dim wb As Workbook
Set wb = Workbooks.Open("C:\drs.xlsx")
With wb.Worksheets("Sheet1")
.AutoFilterMode = False
With .Range("A1:D1")
.AutoFilter Field:=1, Criteria1:="TW", Operator:=xlOr, Criteria2:="W"
.AutoFilter Field:=3, Criteria1:="Windows 7", Operator:=xlOr, Criteria2:="Windows XP"
.AutoFilter Field:=4, Criteria1:="Workstation-Windows"
End With
End With
End Sub

Answer 1

Try following code. I've commented it in details, but if you have some questions, feel free to ask in comments:)
Sub test()
Dim wb As Workbook
Dim sh1 As Worksheet
Dim sh2 As Worksheet
Dim user As Range
Dim lastrowDRS As Long, lastrowMAIN As Long
Dim rng As Range, res As Range
Dim k As Byte
Dim fAddr As String
Application.ScreenUpdating = False
'specify sheet name for main workbook
Set sh1 = ThisWorkbook.Worksheets("Sheet1")
'if drs is already opened
'Set wb = Workbooks("drs.xlsx")
'if drs not already opened
Set wb = Workbooks.Open("C:\drs.xlsx")
'specify sheet name for drs workbook
Set sh2 = wb.Worksheets("Sheet1")
With sh1
'find last row on column A in main wb
lastrowMAIN = .Cells(.Rows.Count, "A").End(xlUp).Row
'clear prev data in columns J:L
.Range("J1:L" & lastrowMAIN).ClearContents
End With
With sh2
.AutoFilterMode = False
'find last row on column A in drs wb
lastrowDRS = .Cells(.Rows.Count, "A").End(xlUp).Row
'apply filter
With .Range("A1:D1")
.AutoFilter Field:=1, Criteria1:="TW", Operator:=xlOr, Criteria2:="W"
.AutoFilter Field:=3, Criteria1:="Windows 7", Operator:=xlOr, Criteria2:="Windows XP"
.AutoFilter Field:=4, Criteria1:="Workstation-Windows"
End With
On Error Resume Next
'get only visible rows in column E
Set rng = .Range("E1:E" & lastrowDRS).SpecialCells(xlCellTypeVisible)
On Error GoTo 0
'loop throught each user in main wb
For Each user In sh1.Range("A1:A" & lastrowMAIN)
'counter for finding entries
k = 0
'find first match
Set res = rng.Find(what:=user.Value, MatchCase:=False)
If Not res Is Nothing Then
'remember address of first match
fAddr = res.Address
Do
'user.Offset(, 9 + k) gives you column J for k=0, K for k=1, L for k=2
user.Offset(, 9 + k).Value = res.Offset(, -3).Value
'increment k
k = k + 1
'find next match
Set res = rng.FindNext(res)
'if nothing found exit stop searcing entries for current user
If res Is Nothing Then Exit Do
'if we already found 3 mathes, then stop search for current user
Loop While fAddr <> res.Address And k < 3
End If
Next user
End With
'close drs wb without saving changes
wb.Close saveChanges:=False
Set wb = Nothing
Application.ScreenUpdating = True
End Sub