There was along discussion about this in VFP new bug: UPDATE with SET RELATION fails Thread #588420.

>Hi all,
>
>any one know how to do something like this:
>
>

>UPDATE table1 set mycolumn = table2.mymatchedcolumn ;
>WHERE (table1.keyid == table2.keyid )
>

>
>Where keyid is a foreign key into table2 from table1. I am using INDEXSEEK(), with lMovePointer turned on, to do similar things now, but it makes me slightly uncomfortable. :)
>
>

>UPDATE table1 set mycolumn = table2.mymatchedcolumn;
>WHERE INDEXSEEK(table1.keyid,.T.,"table2")
>