Compares two column based on the value of a third column's value - vba

Question

What I want to do is create a macro to look at a column (AF) and based on that value, compare column (BI), (BJ), and/or (BK) together and if its false, highlight the compared cells in yellow. I know that's a little hard to follow but this example should help clarify:
My Sheet has the following columns:
Column AF Column BI Column BJ Column BK
PRODUCT Height Length Width
I need a macro to look at the product type and compare the dimensions for that product as follows:
- If product = A, then Length = Width, if not then highlight Length and Width Cells
- If product = B then Length > Width, if not then highlight Length and Width Cells
- If product = C then Width > Height < Length, if not highlight Length, Width, and Height cells
- If product - D then Width = Length < Height, if not highlight Width, Length, and/or Height
My Data starts on row 3 and ends at row 5002.
I have tried researching this and was only able to find solutions that compare two cells then write a third column. I could combine an IF formula and conditional formatting to achieve this but I don't want to have this run all the time as the sheet will be sorted and color coded. I plan to place this macro into a command button.

Answer 1

Suggest to combine Statements such as Select Case, If...Then...Else, together with Operators And, Or. See the following pages:
https://msdn.microsoft.com/en-us/library/office/gg251599.aspx
https://msdn.microsoft.com/en-us/library/office/gg278665.aspx
https://msdn.microsoft.com/EN-US/library/office/gg251356.aspx
After which you should be able to write something that resembles this:
(Code below is just a sample, it will not work)
Select Case Product
Case A
If Length <> Width Then
Rem Highlight Length And Width Cells
End If
Case B
If Length <= Width Then
Rem Insert here the code to highlight Length And Width Cells
End If
Case C
If Width <= Height And Height >= Length Then
Rem Insert here the code to highlight Length, Width, and Height cells
End If
Case D
If Width <> Length And Length >= Height Then
Rem Insert here the code to highlight Width, Length, and/or Height
End If
End Sub
In case you don’t know to highlight the Width, Length and Height Cells; I suggest to do it manually while recording a macro, this shall give a good starting point.

Answer 2

I suggest to work with objects, defining variables for the Data range, each row being validated, the position of the fields to validate, etc. see below code with comments
Sub Highlight_Cells_based_Comparison()
Dim rData As Range
Dim rRow As Range
Dim rCllsUnion As Range
Rem Set variables to hold Fields position within the DATA range
Dim bPosProd As Byte, bPosHght As Byte, bPosLeng As Byte, bPosWdth As Byte
Rem Set variables to hold Fields values
Rem (data type Variant as don't know type of values these fields are holding, change as appropriated)
Rem see https://msdn.microsoft.com/en-us/library/office/gg251528.aspx)
Dim sProd As String, vHght As Variant, vLeng As Variant, vWdth As Variant
Dim lRow As Long
Rem Set Range (assuming it goes from column C to BK - change as needed)
Rem Not starting from column A on porpuse
Set rData = ActiveSheet.Range("C3:BK5002")
Rem Get Fields position from Header row
Rem Suggest to use this method instead of hard coding columns
On Error Resume Next
With rData
bPosProd = WorksheetFunction.Match("PRODUCT", .Rows(1), 0)
bPosHght = WorksheetFunction.Match("Height", .Rows(1), 0)
bPosLeng = WorksheetFunction.Match("Length", .Rows(1), 0)
bPosWdth = WorksheetFunction.Match("Width", .Rows(1), 0)
End With
If Err.Number <> 0 Then Exit Sub
On Error GoTo 0
Rem Loop thru each row excluding header
For lRow = 2 To rData.Rows.Count
Set rRow = rData.Rows(lRow)
With rRow
Rem Get Row Field values
sProd = .Cells(bPosProd).Value2
vHght = .Cells(bPosHght).Value2
vLeng = .Cells(bPosLeng).Value2
vWdth = .Cells(bPosWdth).Value2
Select Case sProd
Case A 'Change value of A as required
Rem If product = A, then Length = Width, if not then highlight Length and Width Cells
Rem If Length <> Width Then Highlight Length And Width 'Cells
If vLeng <> vWdth Then
Set rCllsUnion = Union(.Cells(bPosLeng), .Cells(bPosWdth))
Rem Suggest to use a subroutine for this piece as it's a repetitive task
Rem see https://msdn.microsoft.com/en-us/library/office/gg251648.aspx
GoSub CllsUnion_Highlight
End If
Case B
Rem repeat as in Case A with required changes
Case C
'...
Case D
'...
End Select: End With: Next
Exit Sub
Rem Subroutine to highlight cells
CllsUnion_Highlight:
With rCllsUnion.Interior
.Color = 65535
.TintAndShade = 0
.Pattern = xlSolid
.PatternColorIndex = xlAutomatic
.PatternTintAndShade = 0
End With
Return
End Sub