column names query

On Thu, Sep 7, 2017 at 9:18 AM, <hamann.w@t-online.de> wrote:

is there a simple way to retrieve column names from a query - basically the way psql adds
column headings when I do a select?

How do you do the query? I mean, JDBC, PERL? After all psql is just a
C program doing a query using libpq and can do it, we may provide some
useful info if you show yours first.

Francisco Olarte.

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

SELECT table_name, column_name
FROM information_schema.columns
WHERE table_name = 'your_name';

----- Original Message -----From: hamann w <hamann.w@t-online.de>To: pgsql-general@postgresql.orgSent: Thu, 07 Sep 2017 07:18:12 -0000 (UTC)Subject: [GENERAL] column names query

Hi,

is there a simple way to retrieve column names from a query - basically the way psql addscolumn headings when I do a select?

Best regardsWolfgang Hamann

-- Sent via pgsql-general mailing list (pgsql-general@postgresql.org)To make changes to your subscription:http://www.postgresql.org/mailpref/pgsql-general

On Thu, Sep 7, 2017 at 9:18 AM, <hamann.w@t-online.de> wrote:

is there a simple way to retrieve column names from a query - basically the way psql adds
column headings when I do a select?

How do you do the query? I mean, JDBC, PERL? After all psql is just a
C program doing a query using libpq and can do it, we may provide some
useful info if you show yours first.

Francisco Olarte.

Hi,

I imagine this situation:
I start working on a query... when I am happy with the result, I see a table (with headers) in psql.
Now I can do
\copy (select .... my query here) to /tmp/testfile1
I would like to do something like
\copy (select heading(select .... my query here)) to /tmp/heading_testfile1

Best regards
Wolfgang Hamann

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

SELECT table_name, column_name
FROM information_schema.columns
WHERE table_name = 'your_name';

----- Original Message -----From: hamann w <hamann.w@t-online.de>To: pgsql-general@postgresql.orgSent: Thu, 07 Sep 2017 07:18:12 -0000 (UTC)Subject: [GENERAL] column names query

Hi,

is there a simple way to retrieve column names from a query - basically the way psql addscolumn headings when I do a select?

Best regardsWolfgang Hamann

-- Sent via pgsql-general mailing list (pgsql-general@postgresql.org)To make changes to your subscription:http://www.postgresql.org/mailpref/pgsql-general

Hi,

I am already using something like this (but using pg_attribute table) to retrieve current table layout
for static tables. At the moment I am looking for a solution for ad hoc queries

Example query
select a.col1, case when a.col2 > 0 then a.col3 else b.xcol1 end as mycol3 from a left join b on ....
Expected response
col1 mycol3

Obviously, I could save the result into a temp table and retrieve the table's heading.

Best regards
Wolfgang Hamann

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

On Thu, Sep 7, 2017 at 3:28 PM <hamann.w@t-online.de> wrote:

Example query
select a.col1, case when a.col2 > 0 then a.col3 else b.xcol1 end as mycol3
from a left join b on ....
Expected response
col1 mycol3

This may be overkill, but works:

postgres=# \copy (select 1 as foo, 2 as bar limit 0) to stdout with (format
csv, header, delimiter ' ')
foo bar

Hi Hamman:

On Thu, Sep 7, 2017 at 3:17 PM, <hamann.w@t-online.de> wrote:

I would like to do something like
\copy (select heading(select .... my query here)) to /tmp/heading_testfile1

It's already been pointed out, you can do something using CSV copy
with headers ( Why headers are not allowed in other formats remains a
mistery to me), and LIMIT 0 ( I would try adding AND FALSE to the
where clause better, it may lead to faster response, although I doubt
it) .

Francisco Olarte.

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

On 9/7/2017 12:18 AM, hamann.w@t-online.de wrote:

is there a simple way to retrieve column names from a query - basically the way psql adds
column headings when I do a select?

if you're using libpq to do your queries, PQfname(*result,
column_number) returns the name of that column number.

there are equivalent functions in most other APIs.

--
john r pierce, recycling bits in santa cruz

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general

On Thu, Sep 7, 2017 at 3:28 PM <hamann.w@t-online.de> wrote:

Example query
select a.col1, case when a.col2 > 0 then a.col3 else b.xcol1 end as mycol3
from a left join b on ....
Expected response
col1 mycol3

This may be overkill, but works:

postgres=# \copy (select 1 as foo, 2 as bar limit 0) to stdout with (format
csv, header, delimiter ' ')
foo bar

Hi Manuel,

this works perfectly, many thanks

Wolfgang

--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general