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Re: pgsql and adodb's genID() for unique id sequence...

From: <operationsengineer1(at)yahoo(dot)com>
To: operationsengineer1(at)yahoo(dot)com, pgsql-novice(at)postgresql(dot)org
Subject: Re: pgsql and adodb's genID() for unique id sequence...
Date: 2005-02-02 20:30:49
Message-ID: 20050202203049.86980.qmail@web52410.mail.yahoo.com (view raw or flat)
Thread:
Lists: pgsql-novice
--- operationsengineer1(at)yahoo(dot)com wrote:

> does anybody use this technique?  it is supported by
> pgsql, however, setting it up isn't intuitive to
> this
> newbie.
> 
> -------------------------
> 
> http://phplens.com/lens/adodb/tips_portable_sql.htm
> 
> When you create records, you need to generate unique
> id's for each record. There are two common
> techniques:
> (1) auto-incrementing columns and (2) sequences.
> 
> Auto-incrementing columns are supported by MySQL,
> Sybase and Microsoft Access and SQL Server. However
> most other databases do not support this feature. So
> for portability, you have little choice but to use
> sequences. Sequences are special functions that
> return
> a unique incrementing number every time you call it,
> suitable to be used as database keys. In ADOdb, we
> use
> the GenID( ) function. It has takes a parameter, the
> sequence name. Different tables can have different
> sequences.
> 
> $id = $connection->GenID('sequence_name');
> $connection->Execute("insert into table (id,
> firstname, lastname) values ($id, $firstname,
> $lastname)");
> 
> For databases that do not support sequences
> natively,
> ADOdb emulates sequences by creating a table for
> every
> sequence.
> 
> -----------------------
> 
> i'm left wondering if i need to create a sequence
> table with name 'sequence_name' before this
> technique
> will work.  or, rather, is it just a name i need to
> plug in to uniquely identify a particular sequence
> controlled by the function?
> 
> i'm sorry this is 50% off topic (adodb) and 50% on
> topic (pqsql).
> 
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i found out how to create a pgsql sequence in pgsql
7.4...

http://www.postgresql.org/docs/7.4/static/sql-createsequence.html

i guess my question now becomes - what are the
relative merits of using a serial within each table or
using a sequence that supports all tables (or several
sequences to support tables of my choosing)?


		
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