Subject Re: [ib-support] NOT NULL constraints and the System Tables
Author Martijn Tonies

dropping the constraint touches the RDB$NULL_FLAG column alright. It sets it to 0.

Good. Now, when I try to insert a NULL, it fails - even after committing.

However, when I re-connect, everything is fine. It seems that upon connection (or so - can someone shed a light here?) this kind of meta-data is cached?

Next question: to do the reverse, is setting the RDB$NULL_FLAG to 1 enough to disallow NULLs? Do I have to create records in the RDB$CHECK_CONSTRAINTS and RDB$RELATION_CONSTRAINTS tables to be on the safe side? If so, how do I generate the constraint name?

Martijn Tonies
InterBase Workbench - the developer tool for InterBase and Firebird

Upscene Productions

"This is an object-oriented system.
If we change anything, the users object."

The null flag in rdb$relation_fields and rdb$fields predated
sql and constraints. It can be used alone to disallow nulls.
To allow nulls, you must remove both the constraint and the
null flag.


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