remove duplicates - DISTINCT constraint

[Disrupt07]

I need to populate a table with author names
for example the table name is "author" and it has a field "authorname"
of type text. "authorname" has the following values:
W. Shakespear
J. Smith
W. Shakespear
R. Williams
K. Winslet
... and so on.

Then I want SQLAlchemy to remove the duplicates, so that "W.
Shakespear" will be saved only once.

How can I achieve this using SQLAlchemy?
Thanks

[Glauco]

Disrupt07 ha scritto:

Primary Key or unique constraint do this...

anyway if these names are stored in a list or something similar a
sequence...
firt of all put it in a <type 'set'> ...so automatically your problem is
gone..

In [21]: set( [ 'W. Shakespear', 'J. Smith', 'R. William', 'W.
Shakespear', 'J. Smith'])
Out[21]: set(['W. Shakespear', 'R. William', 'J. Smith'])

Glauco

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Glauco Uri - Programmatore
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[Disrupt07]

Thanks. But what do you mean by "a <type 'set'>" ? Is this a
functionality of SQLAlchemy or of a list or some programming language?

Please explain how to do it in SQLAlchemy because I want to populate
the table initially with all of the data, then I want SQLAlchemy to
save only unique distinct values.

[Glauco]

Disrupt07 ha scritto:

> Thanks. But what do you mean by "a <type 'set'>" ? Is this a
> functionality of SQLAlchemy or of a list or some programming language?
>
>

What's your data sources ? a python list? a text file? another DB?

You can do a sequence of insert into with a unique contraint over that
field so duplicate records will not be stored...

the set otherwise is only usable if you have a list (from a turbo Gear
Form form for example )

a = Authors()
my_authors= [ 'W. Shakespear', 'J. Smith', 'R. William', 'W.
Shakespear', 'J. Smith']

for x in set( my_authors )
a.new( x )

> Please explain how to do it in SQLAlchemy because I want to populate
> the table initially with all of the data, then I want SQLAlchemy to
> save only unique distinct values.
>
>

Glauco

--
+------------------------------------------------------------+
Glauco Uri - Programmatore
glauco(at)allevatori.com

Sfera Carta SoftwareŽ in...@sferacarta.com

[Disrupt07]

@Glauco Thanks.

It worked for me with the set() function.

It would be nice if SQLAlchemy has something to constrain distinct
values on save() or flush().

[Glauco]

Disrupt07 ha scritto:

I think this is not work for SA....

if you have an unique field and do some
insert into table values ( 'boo');
you do an error and the DB do the unique check contraint for you....

in the same manner:

a = Table()
for x in ['boo','boo','boo']:
a.new( x );

i think is better let the DB do his work..... and SA remain the orm :-)

[Eric Ongerth]

On Apr 3, 2:41 am, "Disrupt07" <cvbn...@gmail.com> wrote:
> It would be nice if SQLAlchemy has something to constrain distinct
> values on save() or flush().

You might be interested in this:
http://www.sqlalchemy.org/trac/wiki/UsageRecipes/UniqueObject