Обсуждение: lost in system tables
I am trying to find the equivalent of these two Sybase system columns : check_on_commit (Y/N) - Indicates whether INSERT and UPDATE commands should wait until the next COMMIT command to check if foreign keys are valid. A foreign key is valid if, for each row in the foreign table, the values in the columns of the foreign key either contain the NULL value or match the primary key values in some row of the primary table. nulls (Y/N) - Indicates whether the columns in the foreign key are allowed to contain the NULL value. Note that this setting is independent of the nulls setting in the columns contained in the foreign key. Maybe pg_constaint.condeferrable is appropriate for check_on_commit? I'll appreciate any help Thanks in advance, Emil __________________________________________ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com
On Tuesday 06 December 2005 08:47, Emil Rachovsky wrote: > I am trying to find the equivalent of these two > Sybase system columns : > > check_on_commit (Y/N) - Indicates whether INSERT and > UPDATE commands should wait until the next COMMIT > command to check if foreign keys are valid. A foreign > key is valid if, for each row in the foreign table, > the values in the columns of the foreign key either > contain the NULL value or match the primary key values > in some row of the primary table. > > nulls (Y/N) - Indicates whether the columns in the > foreign key are allowed to contain the NULL value. > Note that this setting is independent of the nulls > setting in the columns contained in the foreign key. > > Maybe pg_constaint.condeferrable is appropriate for > check_on_commit? I'll appreciate any help > > Thanks in advance, > Emil Those parameters are specified when you declare the foreign key. Look here, in the section describing "references": http://www.postgresql.org/docs/8.1/interactive/sql-createtable.html Luca
Emil Rachovsky <zsevgymko@yahoo.com> writes:
> I am trying to find the equivalent of these two
> Sybase system columns :
> check_on_commit (Y/N) - Indicates whether INSERT and
> UPDATE commands should wait until the next COMMIT
> command to check if foreign keys are valid.
I think you are looking for the DEFERRABLE/DEFERRED option of foreign
key constraints.
> nulls (Y/N) - Indicates whether the columns in the
> foreign key are allowed to contain the NULL value.
> Note that this setting is independent of the nulls
> setting in the columns contained in the foreign key.
No such animal in the SQL standard --- though perhaps MATCH FULL
is approximately what you are looking for? Your description as
stated makes no sense at all; either the columns are allowed to
be null, or they're not.
regards, tom lane
Thank you,Tom, As for the description of 'nulls' I have taken it as it is from the Sybase help file :) __________________________________________ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com
> Those parameters are specified when you declare the > foreign key. Look here, > in the section describing "references": > http://www.postgresql.org/docs/8.1/interactive/sql-createtable.html > > Luca Thank you,Luca I know that these parameters are specified when you declare the foreign key, but i need to check them out later from the system tables. The first one must be something like the 'deferrable' column in pg_constaint, but the second is still in vague. Emil __________________________________________ Yahoo! DSL Something to write home about. Just $16.99/mo. or less. dsl.yahoo.com