2005/12/17, Michael Bayer <[EMAIL PROTECTED]>:
>
> On Dec 15, 2005, at 7:41 PM, limodou wrote:
> >
> > I think if I can test the table exist as:
> >
> > if not table.name in sqlite_engine.tables:
> > table.create()
> >
> > This code is ok?
>
>
I'v tried again, If I didn't define the table metadata first, the
sqlite_engine's talbes will be {}. So the code can not work correctly.
> well that doesnt do any kind of SQL to actually ask the database for
> a table.
>
> I think what would happen now if a table doesnt exist, is that youd
> get a Table with no columns, since for the 3 engines that do
> reflection right now its querying a view that returns zero or more rows.
>
> so maybe you could do:
>
> t = Table('mytable', engine, autoload=True)
>
> exists = len(t.columns) > 0
>
> if you are really writing code where you want to create the table if
> it doesnt exist, i guess you could do the above, then if it doesnt
> exist, say:
>
> t = Table('mytable', engine,
> Column('col1' ...),
> Column('col2', ...),
> ...
> redefine=True
> )
> t.create()
>
> "redefine" means to take the table thats currently in the 'tables'
> dictionary and replace its columns with the new ones.
>
> I guess what we are really looking for here is a method called
> create_if_needed(), right ?
>
Yeah, it would be great. Or may be set a option in create() just like:
t.create(notexists=True)
--
I like python!
My Blog: http://www.donews.net/limodou
NewEdit Maillist: http://groups.google.com/group/NewEdit
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