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I need to generate a unique id using field calculator in ArcMap. I am a student and I am having problems finding the script or getting auto increment to work or anything else.

  • if you have a geodatabase(no matter personal or SDE) you can use ArcToolBox and add GlobalId field to your table.It simply adds a unique id to your table.If you insist to use field calculator,you have to provide a code block in VB script or python for it.They don't have any ready to use function to generate unique id except you have a SDE SQL server database,in this case you can have a Guid field in your table and use NewId() (a function declared in SQL server) in field calculator(but not usable in personal geodatabase). – Reza Jul 6 '15 at 5:06
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You'll need to create a quick python script to auto increment through values. In the field calculator, set the Parser to Python. Click Show Codeblock. In your Pre-Logic Script Code block, use:

def UID ():
 global i
 try:
  i += 1
 except:
  i = 1
 try:
  return i
 except:
  return str(i)

Then in your field calculator, just type:

UID ()

Field_Calculator

If you need to start over, click the Python window button on the Standard toolbar, and type del i. Start_Over

  • you need just set i=0 or other value before def. del i isn't necessary – GeoStoneMarten Sep 25 '17 at 13:50

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