On Mon, May 16, 2005 at 12:29:27PM +0200, Lada 'Ray' Lostak wrote: > > I am having small trouble with sequences. I am inserting row into table, > and I need to get value of its 'id' column (sequencen type). As far I know > it have to be done by > > SELECT last_value FORM seq_name > > (or next_val before insert). The above queries are subject to race conditions. For example, if transaction A inserts a record, then transaction B inserts a record, then transaction A queries the sequence, then transaction A will get the sequence value that was given to transaction B, which probably isn't what you want. Use currval() or nextval() instead. http://www.postgresql.org/docs/8.0/interactive/functions-sequence.html http://www.postgresql.org/docs/faqs.FAQ.html#4.11.2 http://www.postgresql.org/docs/faqs.FAQ.html#4.11.3 > Normally, sequences are created by 'table' & 'column' & '_seq' eg. > 'table_id_seq'. > > Now let's rename 'table' to 'table2'. Sequence name wan't renamed. And it's > my problem... I can't simple assume 'sequence id' by table/column... If you're using PostgreSQL 8.0 or later then you can get the sequence name with the pg_get_serial_sequence() function: test=> CREATE TABLE foo (id serial); NOTICE: CREATE TABLE will create implicit sequence "foo_id_seq" for serial column "foo.id" CREATE TABLE test=> ALTER TABLE foo RENAME TO foo2; ALTER TABLE test=> ALTER TABLE foo2 RENAME id TO id2; ALTER TABLE test=> SELECT pg_get_serial_sequence('foo2', 'id2'); pg_get_serial_sequence ------------------------ public.foo_id_seq (1 row) -- Michael Fuhr http://www.fuhr.org/~mfuhr/ ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
