Re: Emulating a sequence

Hi Gerhard. I am back on track. Many thanks for your advice.

Regards,
David

Gerhard Häring wrote:
> David Pratt wrote:
>> [...]
>> I figure excutescript should execute both statements in a single 
>> transaction so it will be as safe way to go. The value will always be 
>> correct without worrying that another connection picked off the next 
>> value before another committed it. [...]
> 
> As I said in the other message, transactions "just work" - with and 
> without executescript().
> 
> - pysqlite (as mandated by the DB-API 2.0) transparently opens 
> transactions for you once you use a DML command (INSERT, UPDATE, DELETE, 
> REPLACE). It also transparently COMMITs if you use a DDL command 
> (CREATE, DROP, ...).
> 
> - Then, just use as many DML commands as you want
> - If you're in a consistent state, use .commit() on the connection object.
> 
> - If you want to roll back your changes, use .rollback() on the 
> connection object.
> 
> A sequence like this is quite common for using the DB-API:
> 
> class DataAccessLayer:
>    ...
> 
>    def some_action(self):
>      try:
>        cur = self.con.cursor()
>        cur.execute(...)
>        cur.execute(...)
>        cur.execute(...)
> 
>        self.con.commit()
>      except:
>        self.con.rollback()
> 
> -- Gerhard
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