Your FOR expression needs to reference a field in TABLE_A not in TABLE_B. You need to have a field in TABLE_A that is to receive the data from TABLE_B.FIELDX. I am guessing that you don't have FIELDX in TABLE_A.

Larry

APPEND FROM TABLE_B for
>A command as simple as:
>
>Select TABLE_A
>Append from TABLE_B FOR FIELDX=.T.
>
>it appends all records, not only FIELDX=.T.
>FIELDX in TABLE_B is a logical field.
>
>I tried also
>
>Append from TABLE_B FOR TABLE_B.FIELDX=.T.
>
>Same result.
>
>Why things apparently so simple are sometimes so complicated?
>
>TIA for your time.
>
>Ulises