>On 1/11/08, André Knappstein, Controlling <[EMAIL PROTECTED]> wrote: >> Once you remove the "NOT NULL" from the domain, this column would >> still remain "not nullable".
You cannot remove the NOT NULL constraint. At 09:33 PM 11/01/2008, Jiri wrote: >OK, now I see. I missed, that the column will be evaluated only for >column definition without domain. Incorrect. All column definitions have a domain, including those that are defined independently of a user-defined domain. All of the domain definitions are stored in RDB$FIELDS. The column RDB$FIELD_SOURCE in RDB$RELATION_FIELDS points to the name of the domain in RDB$FIELDS, viz., RDB$FIELD_NAME. The nullability check is performed on the record that stores the domain definition, i.e. RDB$FIELDS.RDB$NULL_FLAG. >PS: I haven't looked to the reported problem yet, so I'm little >confused, 'cause seems, that the thread has splited into two (about >the wrong results of code and about the not null on column (without >domain). >If there's a problem, I'll try to fix it asap. If there's another >problem (not related to DNET-151), please kick me. :) Just make sure you understand a) the difference between NULL and nullable b) that "nullable" means the field is allowed to be null: it does not mean that it is always null; while "non-nullable" will always mean that the field has been constrained to be NOT NULL c) that the VALUE of 1 on RDB$FIELDS.RDB$NULL_FLAG means that the field is NOT nullable and that the nullABLE flag does not have the value 0: it is null. d) that there will be more potential for confusion in the code, in case the GetSchema call is reading the null indicator field (sqlind) directly from the output descriptor: after the query on the system tables has been prepared, sqlind will be -1 if the field is nullable, or 0 if it is non-nullable. For anyone who doesn't get what null is (and is not), please go to the Documentation Index at the Firebird website and read the Null Guide. Helen ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Firebird-net-provider mailing list Firebird-net-provider@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/firebird-net-provider
