Execute a subroutine when a user enters a trigger into a cell

Question

Example data in Excel:

   A    B    C  
1  9         5  
2  4    y    3  
3  1         9  
4  66        4  
5  5         9  

What I want to d

Answer 1

As siddarth suggested, Worksheet_change() is what you are looking for. Here is how you may achieve your task without any leaks. Paste this code inside the sheet in which you are editing the y value.

Private Sub Worksheet_Change(ByVal Target As Range)

Dim MyRng As Range
Set MyRng = Range("B:B")

Dim PieRng As Range
'Intersect will ensure your current cell lies on column B
Set PieRng = Intersect(Target, MyRng)

'if conditions to ensure trigger code only one cell edited on Col B and is 'y/Y'.
If Target.Columns.Count = 1 And Target.Rows.Count = 1 Then
    If Not PieRng Is Nothing And LCase(Target.Text) = "y" Then
       'Do my stuff here when y / Y are entered in Column B of current sheet
       MsgBox "You entered " & Target.Value & " in Col B"
    End If
End If


End Sub

Let us know if it fails...