Auszug aus der Firebird FAQ
Zitat:
2. If is also possible with a simple system-tables change. While toying with system tables is usually not a good idea, changing the NULL option for a column is a common task, and this has been tested by many users for many years - as all admin tools do it that way:
UPDATE RDB$RELATION_FIELDS SET RDB$NULL_FLAG = 1
WHERE RDB$FIELD_NAME = 'C1' AND RDB$RELATION_NAME = 'T1';
To change from NOT NULL to NULL, use this:
UPDATE RDB$RELATION_FIELDS SET RDB$NULL_FLAG = NULL
WHERE RDB$FIELD_NAME = 'C1' AND RDB$RELATION_NAME = 'T1';
Das geht ja nun in Firebird 3 nicht mehr.
Wie wäre nun der korrekte Weg, wenn man dies nachträglich auf ein Feld aktualisieren möchte?