First, what do you want to show up in the dropdown list? Do you have that list
of available values elsewhere--a different worksheet (within the same workbook)?
If yes, then before you make it a macro, see if that works. (I'm not sure if
you'd want to use all the values that are imported from your external database.)
And I don't think I'd apply data|Validation to all of Column A, too.
I put my list of valid entries in column A of Sheet2. I gave that list a nice
name (myList). Then I could use that in my Data|Validation:
Option Explicit
Sub testme02()
Dim myRng As Range
Dim myList As Range
With Worksheets("sheet2")
Set myList = .Range("A1", .Cells(.Rows.Count, "A").End(xlUp))
myList.Name = "myList"
End With
With Worksheets("sheet1")
With .Range("a1", .Cells(.Rows.Count, "A").End(xlUp).Offset(100, 0))
With .Validation
.Delete
.Add Type:=xlValidateList, AlertStyle:=xlValidAlertWarning, _
Operator:=xlBetween, Formula1:="=myList"
.IgnoreBlank = True
.InCellDropdown = True
.InputTitle = ""
.ErrorTitle = ""
.InputMessage = ""
.ErrorMessage = "Not on list (Warning only)"
.ShowInput = True
.ShowError = True
End With
End With
End With
End Sub
Since you're adding values, I figured a warning might be in order if the value
wasn't part of the list.
And I took all the data in column A (of sheet1) and then went down 100 more
rows--just to give the user some place to add more info.