Re: Emulating a sequence

Hi Greg. Thanks for this suggestion. I guess here I'd still need a 
separate field in a table to increment. I have two scenarios in my code 
where the sequence is needed on a field that is not an auto-incremented 
primary field.

One thing about a real sequence it that once you ask for the next value 
it has a contract not to give that value out again so you are assured 
integrity which is what i really need.

Regards
David

ggivler-zdgUFu1MqnQ@xxxxxxxxxxxxxxxx wrote:
> You could do a Max(column_name) + 1 in your select, this will get the
> Max value of the column. Don't know if that will work for you. Just
> something simple to try.
> 
> Thanks,
> 
> Greg Givler
> Information Technology
> Lockwood®
> 10 Valley Stream Parkway
> Malvern, PA 19355
> Phone: (484) 605-4826
> Email: ggivler-zdgUFu1MqnQ@xxxxxxxxxxxxxxxx
> 
> 
>                                                                               
>                                                              
>                       David Pratt                                             
>                                                              
>                       <fairwinds@xxxxxxxxxx        To:       Tim Golden 
> <mail-5j+KzFhapbd+shrj4D7q1g@xxxxxxxxxxxxxxxx>                                
>              
>                       a>                           cc:       
> pysqlite@xxxxxxxxxxxxxx                                                       
>                       Sent by:                     Subject:  Re: [pysqlite] 
> Emulating a sequence                                           
>                       pysqlite-bounces@list                                   
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>                       s.initd.org                                             
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>                       05/02/2006 09:55 AM                                     
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> 
> 
> Tim Golden wrote:
>> David Pratt wrote:
>>> I was thinking about faking a sequence. My first thought was to
>>> create a sequence table with a single row where a field is a sequence
> 
>>> value and you just increment the value and retreive it as anything
> else.
>>> It's simple but particulary good.
> 
> Eesh! I meant to say not particularly good. I guess it was late when I
> wrote this.
> 
>> No comment as such on the sequence class (never
>> tried it myself). I just wanted to make sure
>> you did know about sqlite's automatic autoincrement
>> value. I know it's not the same as a sequence, but
>> in case you were simply trying to achieve the same
>> effect...
> 
> Hi Tim. I am aware of autoincrementing and have been using it (see tid
> below). I still need something to emulate a sequence. The field I need a
> 
> sequence for is not the primary key. It is a field that keeps track of
> the commit_order for a type of transaction.
> 
> ie.
> create table ztransaction (
>    tid integer not null primary key,
>    packed  boolean not null default false,
>    commit_order integer not null unique,
>    more fields ...
> );
> 
> Hopefully there are a few ideas out there. I'll have to finalize on one
> today in any case :-)
> 
> Regards
> David
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