>>I've looked at Help on ALTER TABLE and I don't see if it requires exclusive access or not.
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>Yes it is
>

Is there any other way to change the structure of the existing table?

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>>Also, does your code require to have the table opened? And why do we have INDBC(.. ) for the field? What good can the value return if it doesn't tell which table?
>
>
>I don't know:-)

I liked Hugo's solution with empty(field('name','table'))