VBA: how to run a macro when certain variable cells change in Excel

Hello everybody.

I've been dealing with how to run a macro when certain cells change in Excel: I mean, under certain conditions a human being could manually change a value in a cell, and then, this change should trigger a recalculation in another cell. I'd like to precise that in my workbook, for internal reasons, it is no possible to use formulas.

Anyway, up to a certain point, the support Microsoft is clear.

https://support.microsoft.com/en-us/help/213612/how-to-run-a-macro-when-certain-cells-change-in-excel

In particular, if I know in advance the range that has to cause a recalculation, no problem:

Set KeyCells = Range("A1:C10")

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Now, my task is harder.

Suppose I've a blank sheet with just a button to run a macro (see attachment "Recalculate-1").

Before running the macro "Update", i don't know what will be the result in terms of populated area.

Suppose, after the running, the new situation as in the second attachment ("Recalculate-2).

I need the green cells triggering recalculation, identified as follows:

- for each value "6" on column B, the green cells have to be - in the same row - from column D to the last populated column in the sheet (in this case, F);
- in event of inserting manually a new value in the green cells, recalculate the sum in column C of the same row (so, suppose I change manually the value in cell E19 from 150 to 100, then the new value in C19 will be 400).

Could anyone help me?
recalculate-1.bmp
recalculate-2.bmp
Paolo CrossiAdministrative employeeAsked:
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Fabrice LambertConsultingCommented:
Why not just a formula ?

Excel work much better with formulas than with VBA.
Subodh Tiwari (Neeraj)Excel & VBA ExpertCommented:
To achieve that, right click the Sheet Tab --> View Code --> Paste the following code into the opened code window.

Private Sub Worksheet_Change(ByVal Target As Range)
If Target.CountLarge > 1 Then Exit Sub
Dim lr As Long, lc As Long
Dim rng As Range
lr = Cells.Find("*", SearchOrder:=xlByRows, SearchDirection:=xlPrevious).Row
lc = Cells.Find("*", SearchOrder:=xlByColumns, SearchDirection:=xlPrevious).Column
If lr < 3 Or lc < 4 Then Exit Sub
On Error GoTo Skip
If Target.Column > 3 And Target.Row > 2 Then
    If Cells(Target.Row, 2) = 6 Then
        Application.EnableEvents = False
        Set rng = Range(Cells(Target.Row, 4), Cells(Target.Row, lc))
        Debug.Print rng.Address
        Cells(Target.Row, 3) = Application.Sum(rng)
    End If
End If
Skip:
Application.EnableEvents = True
End Sub

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Paolo CrossiAdministrative employeeAuthor Commented:
Yes, it works, but very slowly.
I mean: when the macro "Update" is called via the button, it takes several minutes to end the task.

Probably I've to stop some sort of loops created by the process Worksheet_Change.
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Subodh Tiwari (Neeraj)Excel & VBA ExpertCommented:
In the code underneath the Update button, you may disable to events so that the change event code will not be triggered when the Update code tries to write the data onto the Sheet.
To do that, in your Update code, add the following line in the beginning of the code...
Application.EnableEvents = False

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And then enable the events before the Update code ends i.e. add the following line of code before the End Sub line in your Update code.
Application.EnableEvents = True

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If in your Update code, you are using Exit Sub statement anywhere in the code, please remember to enable the events by adding the above line of code before the Exit Sub line.
Paolo CrossiAdministrative employeeAuthor Commented:
Yes, well, now it takes few seconds.

The last step should be: once recalculated

Cells(Target.Row, 3) = Application.Sum(rng)

 for each of the cells included in the ranges, if the cell change value then the new value of the underneath cell (maybe something like cell.offset(1, 0).value ) is cell.Offset(-1, 0).Value / cell.Value
Subodh Tiwari (Neeraj)Excel & VBA ExpertCommented:
The last step should be: once recalculated

Cells(Target.Row, 3) = Application.Sum(rng)
In which code? Do you mean in the Update code?
In that case you need to tweak your Update code to display the correct sum in column C. Isn't it doing that in the existing Update code?

for each of the cells included in the ranges, if the cell change value then the new value of the underneath cell (maybe something like cell.offset(1, 0).value ) is cell.Offset(-1, 0).Value / cell.Value
I am not sure how the values are populated on the Sheet by the Update code. The proposed solution is based on the screenshot of the data you shared and it will produce the desired output once any value gets changed manually.

For your new calculations in the existing code, you may open a New Question by providing the enough description along with a sample file if required.
Paolo CrossiAdministrative employeeAuthor Commented:
Ok, no problem, I figured it out exploiting the ideas showed in your previous posts.
Thank you.
Subodh Tiwari (Neeraj)Excel & VBA ExpertCommented:
You're welcome Paolo!
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