The SQL spec will not help us here, since it doesn't define such a
capability AFAICT. We might do worse than to look at Or*cle's
implementation, which appears to involve a MODIFY keyword.
I find this in the Or*cle 8i documentation examples:
The following statement alters the EMP table and defines andenables a NOT NULL constraint on the SAL column:
ALTER TABLE emp MODIFY (sal NUMBER CONSTRAINT nn_sal NOT NULL);
The docs are opaque enough that I can't actually figure out a BNF
definition for ALTER TABLE MODIFY, and I don't have a working
installation to experiment against. Can any Or*cle users here
enlighten us?
regards, tom lane
