diff options
Diffstat (limited to 'doc/src/FAQ/FAQ.html')
| -rw-r--r-- | doc/src/FAQ/FAQ.html | 40 |
1 files changed, 15 insertions, 25 deletions
diff --git a/doc/src/FAQ/FAQ.html b/doc/src/FAQ/FAQ.html index 410c2c6f551..3a3235eaa6b 100644 --- a/doc/src/FAQ/FAQ.html +++ b/doc/src/FAQ/FAQ.html @@ -10,7 +10,7 @@ alink="#0000ff"> <H1>Frequently Asked Questions (FAQ) for PostgreSQL</H1> - <P>Last updated: Mon Oct 8 23:19:46 EDT 2007</P> + <P>Last updated: Tue Oct 9 15:52:10 EDT 2007</P> <P>Current maintainer: Bruce Momjian (<A href= "mailto:bruce@momjian.us">bruce@momjian.us</A>) @@ -916,38 +916,28 @@ length</TD></TR> ); </PRE> - See the <I>create_sequence</I> manual page for more information - about sequences. + <P>Automatically created sequence are named + <<I>table</I>>_<<I>serialcolumn</I>>_<I>seq</I>, where + <I>table</I> and <I>serialcolumn</I> are the names of the table and + <SMALL>SERIAL</SMALL> column, respectively. See the + <I>create_sequence</I> manual page for more information about + sequences.</P> <H3 id="item4.11.2">4.11.2) How do I get the value of a <SMALL>SERIAL</SMALL> insert?</H3> - <P>One approach is to retrieve the next <SMALL>SERIAL</SMALL> value - from the sequence object with the <I>nextval()</I> function - <I>before</I> inserting and then insert it explicitly. Using the - example table in <A href="#item4.11.1">4.11.1</A>, an example in a - pseudo-language would look like this:</P> -<PRE> - new_id = execute("SELECT nextval('person_id_seq')"); - execute("INSERT INTO person (id, name) VALUES (new_id, 'Blaise Pascal')"); -</PRE> + <P>The simplest way is to retrieve the assigned <SMALL>SERIAL</SMALL> + value with <SMALL>RETURNING</SMALL>. Using the example table in <A + href="#item4.11.1">4.11.1</A>, it would look like this:</P> - You would then also have the new value stored in <CODE>new_id</CODE> - for use in other queries (e.g., as a foreign key to the <CODE>person - </CODE> table). Note that the name of the automatically created - <SMALL>SEQUENCE</SMALL> object will be named <<I>table</I>>_<<I> - serialcolumn</I>>_<I>seq</I>, where <I>table</I> and <I>serialcolumn</I> - are the names of your table and your <SMALL>SERIAL</SMALL> column, - respectively. - - <P>Alternatively, you could retrieve the assigned <SMALL>SERIAL</SMALL> - value with the <I>currval()</I> function <I>after</I> it was inserted by - default, e.g.,</P> <PRE> - execute("INSERT INTO person (name) VALUES ('Blaise Pascal')"); - new_id = execute("SELECT currval('person_id_seq')"); + INSERT INTO person (name) VALUES ('Blaise Pascal') RETURNING id; </PRE> + You can also call <I>nextval()</I> and use that value in the + <SMALL>INSERT</SMALL>, or call <I>currval()</I> <I>after</I> the + <SMALL>INSERT</SMALL>. + <H3 id="item4.11.3">4.11.3) Doesn't <I>currval()</I> lead to a race condition with other users?</H3> |