#Archives Historic SAP Numbers
import arcpy

fc = "U:/Data/Leases.gdb/LeasePlans"
changes = "U:/Data/To_be_Deleted.csv"

#New Field Criteria
field_Name = "Status"
field_Nametype = "Text"
field_NameVal = arcpy.ValidateFieldName(field_Name)

#Adds the new field if it doesn't already exist
fList = arcpy.ListFields(fc,field_Name)
if not fList:
    arcpy.AddField_management(fc, field_Name, field_Nametype, "", "", "")

#List comprehension for IDs
ids = [i for i, in arcpy.da.SearchCursor
       (changes, "SAPNO") if i != None]


Relevant_Fields = ['Property_Ref', 'Status']

#update cursor to Insert 'Archived' rows
with arcpy.da.UpdateCursor (fc, Relevant_Fields) as cursor:
    for SAPNO, in cursor:
        if SAPNO in ids:
            row[1] = 'Archived'
            cursor.UpdateRow()

del cursor