Message-ID: <42899927.9070801@archonet.com>
Date: Tue, 17 May 2005 08:11:35 +0100
From: Richard Huxton <dev@archonet.com>
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To: Joel Fradkin <jfradkin@wazagua.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: getting duplicate number is there a
References: <000e01c55a5f$4d912d00$797ba8c0@jfradkin>
In-Reply-To: <000e01c55a5f$4d912d00$797ba8c0@jfradkin>
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Joel Fradkin wrote:
> I was using SET TRANSACTION ISOLATION LEVEL SERIALIZABLE in MSSQL.
> 
> Is there something similar in postgres to ensure its not in the middle of
> being updated?

Yep - see the SQL COMMANDS reference section under SET TRANSACTION ...
You could use LOCK TABLE too.
See Chapter 12 - Concurrency Control for discussion.

>             sql = "SELECT COUNT(*) FROM tblcase WHERE LocationID = " &
> intLocationID & _
>                   " and substr(casenum,length(casenum)-1,2) = '" &
> right(year(date),2) & "' AND clientnum = '" & _
> 
>                   chrClientNum & "'"
> 
> I will add a select just before doing the insert to see if this helps, its
> not happening a bunch, but 5 6 times a day is still an issue for me.
> 
> I use the count as a segment of my case number so each time a new case is
> entered the count goes up for that location for that year.

I'd be tempted to have a case_numbers table with (year,location,max_num) 
and lock/read/insert to that. Makes everything explicit, and means you 
don't have to mess around with counts/substrings.

--
   Richard Huxton
   Archonet Ltd