Sometimes the data tables I’m using work just fine when I join to shape files and other times some or all of my columns just have <null> in them. What is causing this and how can I fix it?

The format of the file you are joining, both the file name and the fields within it, must conform to a rather strict standard:
  • Don’t use any punctuation (e.g. - & % # / ). Exception: You can use an _ (underscore)
  • Don’t start with fields with a number.
  • Remove all spaces from file and field names.
  • Keep your field names as brief as possible.

If you file name or field name do not conform to this standard, the columns will appear with all <null> value

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