[lug] (OT) postgresql
gsexton at mhsoftware.com
Sun Nov 10 17:44:39 MST 2002
The way you should really do this is to create a sequence:
CREATE SEQUENCE users_seq;
CREATE TABLE Users (
user_id int NOT NULL PRIMARY KEY DEFAULT NEXTVAL('users_seq'),
user_name VARCHAR(12) NOT NULL,
to read the value just inserted:
select CurrVal('users_seq') as newKey
Select max() is incredibly bad. In a multi-user application there are no
protections that two people won't each execute the select max(), and then
perform their insert.
It also will lock the table for the duration of the statement.
Do not do select max().
MH Software, Inc.
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From: lug-admin at lug.boulder.co.us [mailto:lug-admin at lug.boulder.co.us]On
Behalf Of j davis
Sent: 10 November, 2002 3:21 PM
To: lug at lug.boulder.co.us
Subject: [lug] (OT) postgresql
is there a postgresql select query i can enter to specify
the last row of a table...i.e. i want to make a new invoice number based
on the inv_num field of the last customer entry into a table.the only thing
i can think off is to run a loop on the data base using perl to increment
a var + 1 for every row in the table...then use this var to get a query
to the last row...hope this is coherent :)
jd at taproot.bz
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Don't you know I'm loco?"
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