If the above will be in SQL Server 2008, then it's a very good candidate for MERGE command.

Otherwise UPDATE and INSERT with NOT EXISTS condition.


>

>use 1001\customer again in 0 alias oldcustomer shared 
>use 1002\customer again in 0 alias newcustomer shared
>sele newcustomer
>set order to accode
>sele oldcustomer
>set order to accode
>go top
>do while not eof('oldcustomer')
>     scatter memvar
>     sele newcustomer
>     if  not seek(m.accode,'newcustomer','accode')
>         appe blank in newcustomer
>         gather memvar
>    else
>          if empt(newcustomer.address1)
>             repl newcustomer.address1 with m.address1 in newcustomer
>         endif
>          if empt(newcustomer.address2)
>             repl newcustomer.address2 with m.address2 in newcustomer
>         endif
>    endif
>    sele oldcustomer
>    skip
>enddo
>
>

>
>how to do this with sql.
>
>Warm regards,
>mk.