marijnh/Postmodern — pull request #30 by fvides (2013-03-13 20:12:23+00:00)
Title: Extended the :update operation with a :from clause

So it allows to execute updates such as
```sql
update table_to_update
set column_to_update = table_related.column_to_copy_from
from table_many_to_many inner join table_related
on table_many_to_many.fk1 = table_related.pk
where table_to_update.pk = table_many_to_many.fk2;
```
Using an s-sql expression such as:
```common-lisp
(:update 'table-to-update
:set 'column-to-update 'table-related.column-to-copy
:from 'table-many-to-many :inner-join 'table-related
:on (:= 'table-related.pk 'table-many-to-many.fk1)
:where (:= 'table-top-update.pk 'table-many-to-many.fk2)
```