How Can You Lock Rows of Cells in Excel Based on Cell Value? - excel

Question

So I know that one can format cells to be locked and then protect a worksheet to prevent that data being overwritten. But I'm looking to be able to dynamically lock cells within a sheet. From doing some Googling I've tried adapting the below block of code for my needs. The intent is that if column A has a value the rest of the row will be locked so no one can overwrite the rest of the row.
Private Sub Worksheet_Change(ByVal Target As Range)
If Intersect(ActiveSheet.Cells(18, 1), Target) Is Not Nothing Then
If ActiveSheet.Cells(18, 1).Text = "X" Then
ActiveSheet.Range(Cells(18, 2), Cells(18, 20)).Locked = True
Else
ActiveSheet.Range(Cells(18, 2), Cells(18, 20)).Locked = False
End If
End If
End Sub
Any help would be much appreciated, as well as tips for succinctly applying this to every row in the sheet.
UPDATE:
Per BigBen's answer I've revised to the following:
Private Sub Workbook_Open()
Sheets(“Sheet8”).Protect Password:="Secret", UserInterFaceOnly:=True
End Sub
Private Sub Worksheet_Change(ByVal Target As Range)
Dim rng As Range
Set rng = Intersect(Me.Columns(1), Target)
If rng Is Nothing Then Exit Sub
Dim cell As Range
For Each cell In rng
cell.EntireRow.Locked = (cell.Value = "X")
Next
End Sub
But that still doesn't seem to be working...

Answer 1

You need to change the Intersect to test if Target intersects column A, and not a particular cell:
Note also the Not syntax: If Not Intersect... Is Nothing, instead of If Intersect... Is Not Nothing.
Private Sub Worksheet_Change(ByVal Target As Range)
If Not Intersect(Me.Columns(1), Target) Is Nothing Then
Dim rng as Range
For Each rng in Intersect(Me.Columns(1), Target)
If rng.Value = "X" Then
rng.EntireRow.Locked = True
Else
rng.EntireRow.Locked = False
End If
Next
End If
End Sub
Or perhaps a bit more succinctly:
Private Sub Worksheet_Change(ByVal Target As Range)
Dim rng As Range
Set rng = Intersect(Me.Columns(1), Target)
If rng Is Nothing Then Exit Sub
Dim cell As Range
For Each cell In rng
cell.EntireRow.Locked = (cell.Value = "X")
Next
End Sub