Re: Passinf field name

"Jonathan S. Katz" <[email protected]> Sat, 3 Nov 2018 13:47:17 -0400

Newsgroups	gmane.comp.db.postgresql.sql
Message-ID	<[email protected]>

> On Nov 3, 2018, at 1:40 PM, Graeme Gemmill <[email protected]> wrote:
> 
> 
> Help please: Trying to construct a query where a field name has to be passed.
> Database wbdata has a field “date timestamp with timezone”.
> cursor.execute("SELECT * FROM wbdata ORDER BY date;")
> works.
> cursor.execute("SELECT * FROM wbdata WHERE date > %s", (starttime,))
> works.
> I read in your FAQs that I have to use psycopg2.sql to pass a field name into the query, so to select a subset of wbdata where date is > startdate and the output is sorted by date, I tried
> cursor.execute(
> sql.SQL("SELECT * FROM wbdata ORDER BY %s WHERE date > %%s" % [sql.Identifier("date")], [starttime]))
> 
> which gives me an error:
> TypeError: __init__() takes 2 positional arguments but 3 were given
> What is a correct formulation please?

If you’re just trying to order by the “date” column, this should work fine:

cursor.execute("SELECT * FROM wbdata WHERE date > %s ORDER BY date", (starttime,))

Best,

Jonathan

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