Copy all data from one field into another field within the same table

Key fields must be unique. I can't reconcile your title with the body of your message - they seem  to be talking about different issues. Clarify.

Reason I am copying is so I can use the new field I copied into as a key field.

Ruby,

In fact the best solition for your lat/ long issue is to make a formula field to concatenate the lat/ long together like 123-456. I think you have that already done.

In fact, a little known secret is that a formula in fact can be the Key field to a table. You just need to type in the API call by hand into your browser.

Just get to the table and after the ? Hand type

act=API_SetKeyField&fid=99

When 99 is the field ID number.

You can double check the syntax in the API help guide, but I think that is it. I would turn off App tokens when you do that or else you would need to supply one to make that change

Then you don�t need form rules to copy across a formula to a text key field!

I will try it. Thanks.
I didn't concatenate because I was worried at some point the combined value would no longer be unique. How many decimal places to strip off? I have the entire Long and Lat value in there separated by a space using the List function. Reason I used space and did not use another symbol like  - or / is when I exported to CSV, then I noticed it changed the value of the combined data to some single value (like it was doing a calculation).

I can't really suggest if you would want to strip off decimals.  It's a text field, so text is text it will not truncate or round) and they will be unique if they are even a tiny bit different. I guess it depends on your application needs as to how many decimals to maintain.

You are brilliant! Thanks.

Steps I took:
App settings: App Properties>Security>I clicked on Manage tokens but no tokens listed. Then I unchecked the box Require Application Tokens.
At the table I typed in act=API_SetKeyField&fid=33 after the ? and removed the "a=td" but got an error so I changed act= to a=

It worked! I looked in my Table, that field has been set to be the Key field.

Do I need to worry about the security concern from not requiring app tokens?

The only reason I suggested to turn off App Tokens was so that when you hand typed that URL once, you didn't not have to also  type &appoken= xxxhedqkurfkhndjdksk

Feel free to turn to back on now that the Key field is changed. 

I hesitate to advise on this forum whether you should or should not leave them enabled.  It is an extra layer of security.

Thank you once again for the solid advice. Your experience carries a great deal of weight. I will turn it back on.