Re: get first and last row in one sql as two columns

[Tom Smith <tomsmith1989sk@xxxxxxxxx>]

Thanks for suggestion.  I could use two separate sqls, but I am looking to get it in a single sql.

I just compiled and installed (under postgres id)  first_last_agg C extension.
http://pgxn.org/dist/first_last_agg/

it WORKED under postgres user with sample
select first(column1), last(column1) from (values (null),(1),(3),(null)) as x
but somehow when I run under other users, it say

ERROR:  function first(integer) does not exist

below is the control file ,  I can not find out why I can not run under other user ids.
Any help would be appreciated.

# first_last_agg extension
comment = 'first() and last() aggregate functions'
default_version = '0.1.4'
module_pathname = '$libdir/first_last_agg'
relocatable = false
schema = pg_catalog
superuser = false

On Wed, Sep 2, 2015 at 7:47 PM, Melvin Davidson <melvin6925@xxxxxxxxx> wrote:

Try this:

SELECT
  (SELECT <your_column>
     FROM <your_table>
     ORDER BY <your_column> offset 0 LIMIT 1) ,
  (SELECT <your_column>
     FROM <your_table>
     ORDER BY <your_column> OFFSET (SELECT COUNT(*) ) LIMIT 1)
   FROM <your_table> LIMIT 1;

On Wed, Sep 2, 2015 at 7:27 PM, Rob Sargent <robjsargent@xxxxxxxxx> wrote:

On 09/02/2015 05:14 PM, Tom Smith wrote:

Hi:

I need to get the first and last tow in one sql like below

select first(col1), last(col1) from table order by col1

I saw some posting in wiki with a custom function (or C extention)

to do this.   Is it widely used and reliable?
https://wiki.postgresql.org/wiki/First/last_(aggregate)

I am wondering why these two functions are not part of postgresql built-in

functions as it has many use cases

Thanks

If you're ordering by col1, does

select min(col1), max(col1) from table order by col1

not do the trick;

--

Melvin Davidson
I reserve the right to fantasize.  Whether or not you
wish to share my fantasy is entirely up to you.