Gavan Schneider wrote:
> Taking a different tangent ...
Good idea.
> Is there anything in the SQL standards about NOT NULL
> constraints being deferrable?
>
> To my mind we should not consider implementing non-standard
> behaviour, but if something is in the standard I can't see why
> it shouldn't be implemented, esp. when there is no compulsion
> for it to be used.
ISO/IEC 9075-2:2003 says:
Chapter 11.4 (<column definition>):
<column constraint definition> ::=
[ <constraint name definition> ] <column constraint> [ <constraint
characteristics> ]
<column constraint> ::=
NOT NULL
| <unique specification>
| <references specification>
| <check constraint definition>
Chapter 10.8 (<constraint name definition> and <constraint characteristics>):
<constraint characteristics> ::=
<constraint check time> [ [ NOT ] DEFERRABLE ]
| [ NOT ] DEFERRABLE [ <constraint check time> ]
<constraint check time> ::=
INITIALLY DEFERRED
| INITIALLY IMMEDIATE
So yes, the standard caters for deferrable NOT NULL constraints.
Moreover:
Chapter 10.8, General Rules
1) A <constraint name> identifies a constraint. Let the identified constraint
be C.
2) If NOT DEFERRABLE is specified, then C is not deferrable; otherwise it is
deferrable.
So deferrable should be the default.
Yours,
Laurenz Albe
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