Re: default value based on select

On Sat, 5 Apr 2008, Pedro Doria Meunier <pdoria(at)netmadeira(dot)com> writes:
> Is it possible to have a table's column default value set to some form of
> select?

AFAIK, you cannot provide sub-selects in the default values of a
field. E.g.

CREATE TABLE foo (bar int DEFAULTS (SELECT ...), ...);

For this, I know two solutions:

1. You can create an SQL function that issues the related sub-select and
call this function as the default value of the column.

2. Create a BEFORE INSERT/UPDATE trigger that issues the related
sub-select if related column appears to be un-specified.

Regards.