You can either do this using the field calculator, or an update cursor. Are the RUseCode values a text string or are they integers? If they are numbers, you will not need the quotes around the find or replace values.Field Calculator:Pre-logic
def Replace( field, find, replace ):
if field != find:
return field
elif field == find:
return replace
Expression
Replace( !RUseCode04!, "999", "9999")
[ATTACH=CONFIG]25605[/ATTACH]Or you could try and use an update cursor to do it all at once. You can just put all of your fields you want to do this to in the "fields" list.
import arcpy
fc = r'C:\path\to_your\feature_class'
fields = ['RUseCode02', 'RUseCode03', 'RUseCode04']
rows = arcpy.UpdateCursor(fc)
for row in rows:
for field in fields:
if row.getValue(field) == '999':
row.setValue(field, '9999')
rows.updateRow(row)
del row, rows
I think your original code should have worked by the way...Did you set the parser to Python first and supply those expressions one at a time?