Re: SET NULL / SET NOT NULL

At 18:34 20/02/02 -0800, Thomas Lockhart wrote:
>> > ALTER TABLE blah ALTER COLUMN col [ALLOW NULL | NOT NULL]
>> FWIW, I like this syntax too.
>
>What would be the drawbacks to having all portions after "col" in the
>example above be *exactly* the same as the clauses allowed in CREATE
>TABLE? So, this would be
>
> ALTER TABLE tab ALTER COLUMN col [ NULL | NOT NULL ]

This looks fine to me. The spec only talks about CHECK constraints in ALTER
TABLE, but if I had to guess the most spec-like syntax, it would be:

ALTER TABLE tab ALTER COLUMN col DROP NOT NULL

which does not seem particularly good; preserving the syntax from table
creation has to be TWTG. Do we really allow:

CREATE TABLE FOO(BAR INT NULL)

?

>In that same line of thought, how about making it more closely mimic the
>original CREATE TABLE syntax? Something like

Because the SQL spec does have ALTER TABLE...ALTER COLUMN; so we should
stick with the same syntax.

>Hmm. Or if we are going to eventually allow altering column types then
>one could include the type also.

Definitely; Chris' suggestion seems pretty good to me.

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