--- In IBDI@y..., "Claudio Valderrama C." <cvalde@u...> wrote:
<...>
> > The SQL standard says that, by default, all columns allow nulls,
> > unless there is a NOT NULL column constraint or equivalent. <...>
>
> <...> I admit my question was twofold: what happens then once a
column was
> defined, is there any syntax to change the NULL/NOT NULL state of
such
> column?
In the SQL standard, NOT NULL is just a constraint, so you'd add or
remove it the same way you would add or remove other constraints.