Re: Sequence

From: Simon Mitchell <pgsql(at)jseb(dot)com>
To: Alan Roberto Romaniuc <romaniuc(at)klais(dot)com(dot)br>, "pgsql-jdbc(at)postgresql(dot)org" <pgsql-jdbc(at)postgresql(dot)org>
Subject: Re: Sequence
Date: 2003-01-12 01:19:19
Message-ID: 3E20C297.9020201@jseb.com
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Alan,
Just doing some test from psql prompt.

After your insert into the table the id sequence is available by

select currval('table_id_seq');
currval
---------
5006
(1 row)

If your session has not done an insert you should get an error.
select currval('table_id_seq');
ERROR: table_id_seq.currval is not yet defined in this session

Do a describe (\d) on your table to check seq name.

So this is equivalent to MySql > last_insert_id() .

***************************************************
If you wont the last value of the sequence (which could be your current
session or another session) you can select it with

SELECT last_value FROM table_id_seq;
last_value
------------
5006
(1 row)

**This is not transaction safe as another session could have done an
insert. Please use select currval('table_id_seq');**
It is just nice to know.
***************************************************

Simon

Dave Cramer wrote:

>Alan,
>
>You can't, get the sequence before and insert it.
>
>Dave
>On Thu, 2003-01-09 at 14:35, Alan Roberto Romaniuc wrote:
>
>
>>I have a table with sequence field (id).
>>
>>I insert a new row in this table, and I would like to get the sequence
>>number that postgresql assign to id.
>>
>>How can I get it??? ... Max function is not nice.......
>>
>>jdbc2 ....
>>
>>
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