Re: [GENERAL] column names query

2017-09-08 Thread hamann . w 
>> On Thu, Sep 7, 2017 at 3:28 PM  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




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Re: [GENERAL] column names query

2017-09-07 Thread John R Pierce 

On 9/7/2017 12:18 AM, haman...@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



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Re: [GENERAL] column names query

2017-09-07 Thread Francisco Olarte 
Hi Hamman:

On Thu, Sep 7, 2017 at 3:17 PM,   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.


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Re: [GENERAL] column names query

2017-09-07 Thread Manuel Gómez 
On Thu, Sep 7, 2017 at 3:28 PM  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

Re: [GENERAL] column names query

2017-09-07 Thread hamann . w 
>> SELECT table_name, column_name
>> FROM information_schema.columns
>> WHERE table_name = 'your_name';
>>  
>> - Original Message -From: hamann w To: 
>> pgsql-general@postgresql.orgSent: Thu, 07 Sep 2017 07:18:12 - 
>> (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 





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Re: [GENERAL] column names query

2017-09-07 Thread hamann . w 


>> On Thu, Sep 7, 2017 at 9:18 AM,   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




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Re: [GENERAL] column names query

2017-09-07 Thread stimits 
SELECT table_name, column_name
FROM information_schema.columns
WHERE table_name = 'your_name';
 
- Original Message -From: hamann w To: 
pgsql-general@postgresql.orgSent: Thu, 07 Sep 2017 07:18:12 - (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



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Re: [GENERAL] column names query

2017-09-07 Thread Francisco Olarte 
On Thu, Sep 7, 2017 at 9:18 AM,   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.


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