python script for attribute table field calculator

[FaithWebster]

I'm using ArcMap 10.2. I have 2 columns in a joined table that I need to compare. They need to have the exact same content, and there are about 3,000 rows. I tried this: (changed field names for security)

[column1] ==!column3!
   return yes
else:
   return no

the Field calculation failed. I think I'm forgetting something really basic in the python script. I would appreciate any advice. 

Thank you!

[DanPatterson_Retired]

Rather than fiddling around with a script...

1  Add a text/string field to your table... call it ... Check ... or something

2 Select by attribute ....  field1 == field2

3  make ... Check... the active field and open the field calculator and type 'yes' with the single quotes around the word

4  from the table, hit the switch selection button to get the reverse

5  from the Check field... type 'no'

you should now have all records filled ...Unless... you have Null values in your fields since a value won't compare to null.  If you have any of those, then get back

[FaithWebster]

Thank you! That is a much easier solution! 

[FaithWebster]

Just a note: the select by attribute uses SQL and the expression was field 1=field 2. it worked perfectly!

[RebeccaStrauch__GISP]

besides what Dan said, always make sure you have a space on both sides of the ==      at least in your post it looks like the space is missing after the before the !    (which may just be a typo in the post)

[BlakeTerhune]

When using an if statement, you probably have to use the field calculator code block option. You also mixed up the field name syntax between VB and Python.

code block:

def compareCalc(col1, col3):
    if col1 == col3:
       return 'yes'
    else:
       return 'no'‍‍‍‍‍‍‍‍‍‍

expression:

compareCalc(!column1!, !column3!)‍‍