Compare And Copy Data From One Sheet To Another.

SalesImport contains sales data, and one column of that sheet is a unique reference number to identify the agent responsible for those sales.

Main contains much more data, and I need to transfer sales data from SalesImport to Main in the most efficient, automated way possible - on a monthly basis most likely... but possibly weekly or even ad-hoc at a later date... so it really does need to be quite quick.

At the moment I have come up with an idea to loop through each row on the SalesImport page, and for each row, compare the unique reference number (Column I) with the unique reference numbers on the Main sheet, (Column C). If they match, set the value of the sales column on Main to the same value as the sales column on the SalesImport sheet.

However, this is not working as i would hope, and doesn't copy anywhere near all the rows I know are found in both sheets.

Sub SalesDataImport_Main()
Dim c As Long, d As Long, Limit1 As Long, Limit2 As Long, Limit3 As Long, sh1 As Worksheet, sh2 As Worksheet, sh3 As Worksheet

Set sh1 = Sheets("Main")
Set sh2 = Sheets("SalesImport")

Limit1 = sh1.Cells(Rows.Count, 3).End(xlUp).Row
Limit2 = sh2.Cells(Rows.Count, 9).End(xlUp).Row

For c = 2 To Limit2
sh2.Cells(c, 9).Select
For d = 3 To Limit3
If sh1.Cells(d, 3).Value = sh2.Cells(c, 9).Value Then
sh2.Cells(c, 27).Value = "In Main List"
Else: sh2.Cells(c, 27).Value = "Not in Main List"
End If
Next d
Next c
End Sub