[Interest] "Last selected row id" QSqlQuery?

[程梁]

Almost each database has its own syntax to get last selected row id.
So your question is not QSqlQuery's business but SQL statement.
You could use SELECT @@IDENTITY for MSSQL, SELECT LAST_INSERT_ID() for MYSQL,
SELECT seq.nextval for Oracle, etc.

SELECT MAX(id) may get incorrect id if it is used in mutil-threaded systems, IMO.
Well, I'm not sure about this.

Cheng Liang
Nanjing, China
http://www.devbean.net

From: adrian.stern at screenfood.com
To: wewolski at gmail.com; interest at qt-project.org
Date: Wed, 22 May 2013 08:31:47 +0000
Subject: Re: [Interest] "Last selected row id" QSqlQuery?








Take a look at this:
 
http://blog.sqlauthority.com/2007/03/25/sql-server-identity-vs-scope_identity-vs-ident_current-retrieve-last-inserted-identity-of-record/
 
 

 
Freundliche Grüsse / Best Regards / Meilleures salutations
Adrian Stern

 


From: interest-bounces+adrian.stern=screenfood.com at qt-project.org
 [mailto:interest-bounces+adrian.stern=screenfood.com at qt-project.org] On Behalf Of
Adrian Stern

Sent: 22 May 2013 10:30

To: Witold E Wolski; interest at qt-project.org

Subject: Re: [Interest] "Last selected row id" QSqlQuery?


 

In MSSQL there is a command called SCOPE_IDENTITY() which returns the id of the last inserted row. There is probably something similar in whatever
 dbms you are using.
 
Otherwise I would need some more information about our environment.
 
 
Freundliche Grüsse / Best Regards / Meilleures salutations
Adrian Stern
 
From:
interest-bounces+adrian.stern=screenfood.com at qt-project.org [mailto:interest-bounces+adrian.stern=screenfood.com at qt-project.org]
On Behalf Of Witold E Wolski

Sent: 22 May 2013 10:26

To: interest at qt-project.org

Subject: [Interest] "Last selected row id" QSqlQuery?
 





How can I get efficiently the id of the last insterted row?

A the moment I am using :

SELECT MAX(id) from table.

Which isn't efficient. 



How can i do it more efficiently but stay database agnostic.

best

Witold





 







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