Re: How to send multiple SQL commands from Python?

On Saturday 10 October 2009 12:27:39 pm Adrian Klaver wrote:
> On Saturday 10 October 2009 12:09:29 pm Kynn Jones wrote:
> > I am porting some code from Perl to Python; in the Perl original I use
> > either DBI::do or a rickety home-built module to pass multiple SQL
> > statements (as one single block of SQL) to the Pg server. The typical
> > usage is something like this:
> > $dbh->do( <<EOSQL );
> > ALTER TABLE $xn OWNER TO xdev;
> > GRANT ALL ON TABLE $xn TO xdev;
> >
> > REVOKE ALL ON TABLE $xn FROM PUBLIC;
> > GRANT SELECT ON TABLE $xn TO PUBLIC;
> > EOSQL
> >
> >
> > How can I do this sort of thing from Python?
> >
> > I've looked into the docs for psycopg2, but I can't find anything like
> > the do command used above. Did I overlook it? If not, what can I use
> > instead?
> >
> > I'm not wedded to psycopg2, in fact its lack of documentation worries me;
> > if there's a better alternative that I can use from Python please let me
> > know.
> >
> > TIA!
> >
> > kynn
>
> One way
> Using psycopg2
> DSN = "dbname=? user=? port=? host=?"
> con = psycopg2.connection(DSN)
> cur = con.cursor()
> cur.execute(statement1)
> cur.execute(statement2)
> ....
> con.commit()
>
> Another way, not tested, is triple quote entire block above and pass it to
> cur.execute.
>
> --
> Adrian Klaver
> aklaver(at)comcast(dot)net

I missed the part where you wanted to do it as one block with variables already
substituted.

For that I usually do something like:

sql_str = "ALTER TABLE " + $xn + " OWNER TO xdev;"
sql_str += "GRANT ALL ON TABLE " + $xn + " TO xdev;"
sql_str += "REVOKE ALL ON TABLE " + $xn + " FROM PUBLIC;"
sql_str += "GRANT SELECT ON TABLE " + $xn + " TO PUBLIC;"

cur.execute(sql_str)

On a side note the Psycopg mailing list is:
http://lists.initd.org/mailman/listinfo/psycopg

It is very helpful and makes up for the documentation issues.

--
Adrian Klaver
aklaver(at)comcast(dot)net