Hello Aldo, > My questions are the following:
> 1) Is the intended effect to fill behind the scenes a newly created > field with its default value when there is a not null constraint ? No. Only inserts subsequent to the commit of the DDL for the new field will use the default in the case where no value is provided. Note, also, that default values apply only to inserts and only where the field is absent from the field list for the insert. > 2) Could this behind the scenes filling fail because of an update or > insert of another concurrent transaction ? There is no "behind the scenes filling". If you add a NOT NULL field to an existing table, or change a nullable field to NOT NULL, then you are responsible for filling the field yourself, immediately after the DDL is committed. update mytable set newfield = 1 where newfield is null update mytable set existingfield = 1 where existingfield is null As for the effect on concurrent transactions, you should not be attempting to change the structure of a table while it is in use. HB > ------------------------------------ > Posted by: Aldo Caruso <[email protected]> > ------------------------------------ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Visit http://www.firebirdsql.org and click the Documentation item > on the main (top) menu. Try FAQ and other links from the left-side menu > there. > Also search the knowledgebases at > http://www.ibphoenix.com/resources/documents/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > ------------------------------------ > Yahoo Groups Links -- Kind regards, Helen Borrie
