Using nested formula in VBA - excel

Question

I'm working on problem that necessitates the use of nested formulas in excel. For eg:
I have a column for errors and one for its analysis
Error Analysis
Enter a valid material number Invalid Material
Eg errors:
Enter a valid material number; The material number 1234 does not
exist.
PO number XYZ does not exist.
VIN number 123 does not exist.
Country of origin AB does not exist.
I have a compendium of such errors and their analyis in the next sheet, and I'm using VLOOKUP in conjuction with FIND to lookup the analysis for the known errors.
=VLOOKUP(LEFT(F2, FIND(" ", F2, FIND(" ", F2) + 1) - 1)&"*", 'Sheet2'!A:B, 2, 0)
What i'm trying to do here is extract the first two words from the error and append a * to it and use it in VLOOKUP.
It would be something like Vlookup "PO number *" in the other sheet and get the analysis for it. Asterisk is because I don 't get the same number daily. And I also know that the extracted first two words of the error will be unique. (I know that error with "Enter a" as the first two words will not appear again).
Now I get errors in the same column so I thought of making a button and writing a code which uses the above formula.
I tried to modify some code off the net, but I'm not getting anywhere with it. I'm totally new to VBA. It'd be great if you can provide a snippet for this. I'll try to replicate the procedure for other needs.
This code seems to be working for now
Sub PopulateAnalysis()
Dim an_row As Long
Dim an_clm As Long
Dim lft As String
Dim st_num As Integer
Dim fin As String
Dim searchStr As String
Dim soughtStr As String
Table1 = Sheet1.Range("F2:F6") 'ErrorColumn from Error table (How do I make the range dynamic??)
Table2 = Sheet5.Range("A1:B6")
an_row = Sheet1.Range("G2").Row ' Populate this column from the analysis table on sheet2
an_clm = Sheet1.Range("G2").Column
For Each cl In Table1
'How do I translate the above formula into VBA statements??
st_num = InStr(InStr(cl, " ") + 1, cl, " ")
lft = left(cl, st_num - 1)
fin = lft & "*"
Sheet1.Cells(an_row, an_clm) = Application.WorksheetFunction.VLookup(fin, Table2, 2, True)
an_row = an_row + 1
Next cl
MsgBox "Done"
End Sub

Answer 1

This should work. You don't need the debug lines of course ;)
Sub PopulateAnalysis()
Dim rngTableWithErrors As Range
Dim rngTableWithAnalysis As Range
Application.ScreenUpdating = False
'set the range for Table with error, Table1 on sheet 1
With Sheets(1) 'change to name of the sheet, more reliable than index num.
Set rngTableWithErrors = .Range("F2:F" & .Cells(.Rows.Count, 6).End(xlUp).Row)
Debug.Print rngTableWithErrors.Address
End With
'set the range for Table with Analysis, Table 2 on sheet 2
With Sheets(2) 'change to name of the sheet, more reliable than index num.
Set rngTableWithAnalysis = .Range("A1:B" & .Cells(.Rows.Count, 2).End(xlUp).Row)
Debug.Print rngTableWithAnalysis.Address
End With
'formula for cell G2
'=VLOOKUP(LEFT(F2;FIND(" ";F2;FIND(" ";F2)+1)- 1)&"*";Sheet2!A1:B23;2; 0)
rngTableWithErrors.Offset(0, 1).FormulaR1C1 = _
"=VLOOKUP(LEFT(R[0]C[-1],FIND("" "",R[0]C[-1],FIND("" "",R[0]C[-1])+1)-1)& ""*"",Sheet2!R1C1:R" & rngTableWithAnalysis.Rows.Count & "C2,2, 0)"
Application.ScreenUpdating = True
MsgBox "Done"
End Sub
Notes
You can notice, that we are setting the upper left cells of ranges manually. It's better practice to somehow find the upper left cells (using Find method is my favorite) and work from there. You never know, how the user will change the worksheet - i.e. add new rows, columns etc.