In addition to Christopher's reply you can do the same by setting relation from tableB to tableA and

replace field1 with tableA.field1 in TableB for found('TableA')

It's the same, as UPDATE command. I'm not sure, what would be faster.

>I friend of mine did a program as below and complains
>scan is too low.
>He as 3,000,000 records
>He wonder if the struct is correct or is there a better way
>to do that.
>Tables are into a database
>
>sele tabela A
>set order to indice
>sele tabela B
>go top
>scan
>sele tabela A
>seek(tabela B.campo)
>if found()
>replace value from tabelaB to tabelaA
>sele tabela B
>endif
>endscan