Re: Trying to understand why same SQL returns different results.

On 11/20/2012 12:33 PM, Neil Tiffin wrote:
> When I run the SQL directly from psycopg and from a plpgsql function each produces different results. One returns two columns and the other only returns one column.
>
> For example.
>
> def sql_test1():
> cur = CONN.cursor()
> cur.execute("""
> CREATE OR REPLACE FUNCTION get_some_text()
> RETURNS RECORD AS $$
> DECLARE
> result RECORD;
> BEGIN
> SELECT 'some text' AS colume1, 'some more text' as column2 INTO result;
> RETURN result;
> END;
> $$ LANGUAGE plpgsql;""")
>
> print('test 1')
> cur.execute("""SELECT 'some text' AS colume1, 'some more text' as column2;""")
> print (cur.description)
> print (cur.fetchone())
>
> print ('test 2')
> cur.execute("""SELECT get_some_text();""")
> print (cur.description)
> print (cur.fetchone())
>
> CONN.commit()
> cur.close()
>
> Output:
> test 1
> (Column(name='colume1', type_code=705, display_size=None, internal_size=-2, precision=None, scale=None, null_ok=None), Column(name='column2', type_code=705, display_size=None, internal_size=-2, precision=None, scale=None, null_ok=None))
> ('some text', 'some more text')
>
> test 2
> (Column(name='get_some_text', type_code=2249, display_size=None, internal_size=-1, precision=None, scale=None, null_ok=None),)
> ('("some text","some more text")',)
>
> Is this the expected results and I am misunderstanding something? Or is this a bug?

Expected.
In the first case you are returning two columns.
In the second a single record.

Running in psql explains it better:

First case:

test=> SELECT 'some text' AS colume1, 'some more text' as column2 ;
colume1 | column2
-----------+----------------
some text | some more text
(1 row)

Second case:

test=> SELECT get_some_text();
get_some_text
--------------------------------
("some text","some more text")
(1 row)

>
> Neil
>
> Python 3.3.0
> Mac OS X 10.7.5, Postgresql 9.1.2, psycopg git clone,
>

--
Adrian Klaver
adrian(dot)klaver(at)gmail(dot)com