[cvsnt] Re: Audit DB: commitlog.sessionid is always 0

[Bo Berglund]

On Fri, 06 Jan 2006 08:30:40 +0100, Olaf Groeger <Olaf.Groeger at gmx.de>
wrote:

>Tony Hoyle wrote:
>
>> Olaf Groeger wrote:
>>> Hmm, i'm not sure that i understood you. You suppose that the insert in
>>> sessionlog doesn't returns the correct id but 0, which causes the 0 in
>>> the successesive inserts into commitlog and historylog?
>> 
>> Basically, yes.  There's no standardised way in SQL of returning the id
>> of the last insert... indeed some (Firebird) can't do it at all.  In
>> ODBC you can use select @@identity but that needs to be supported by the
>> underlying driver.  Most of the native drivers have a function that
>> returns it.
>> 
>Ah, ok. Now i understand. Well, this is because there is no standard about
>"identity" columns. MSSQL manages them entirely (you can disable this),
>PostGreSQL automatigally creates a sequence and auto-increments
>(overwritable), MySql has an auto-increment feature, IIRC. But many
>databases doesn't support such auto-valued columns at all (Oracle).
>Consequently only those databases with auto values provide a way to return
>the generated value.
>
>Back to the original posting: You're right: select @@identity doesn't work
>with PostGreSQL. The error from the log is "ERROR:  column "identity" does
>not exist".
>

SQLite does work fine though...


/Bo
(Bo Berglund, developer in Sweden)