Обсуждение: BUG Report - Select distinct on

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                         POSTGRESQL BUG REPORT TEMPLATE
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Your name        :    Dirk Elmendorf
Your email address    : delmendo@rackspace.com


System Configuration
---------------------
   Architecture (example: Intel Pentium)      : Intel Pentium

   Operating System (example: Linux 2.0.26 ELF)     :RedHat Linux 6.1/ 2.2.12-20
   PostgreSQL version (example: PostgreSQL-6.5.1):   PostgreSQL-7.0
   Compiler used (example:  gcc 2.8.0)        :    egcs-2.9.66


Please enter a FULL description of your problem:
------------------------------------------------
Can not use the select distinct sql statement.






Please describe a way to repeat the problem.   Please try to provide a
concise reproducible example, if at all possible:
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create table test
(
    label text
);

select distinct on label label from test;

ERROR:parser: parse error at or near "label";
select label from test;
label
---------
(0 rows)




If you know how this problem might be fixed, list the solution below:
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--
______________________________________________________________________
Dirk Elmendorf, CTE                                Main: 210-892-4000
Rackspace,Ltd.                                   Direct: 210-892-4005
Weston Center                                       Fax: 210-892-4329
112 East Pecan, Suite 600                Email:delmendo@rackspace.com
San Antonio,  TX 78205                     <http://www.rackspace.com>

Dirk Elmendorf <delmendo@rackspace.com> writes:
> select distinct on label label from test;

> ERROR:parser: parse error at or near "label";

The syntax is different in 7.0.  Try

select distinct on (label) label from test;

Sorry about the loss of backwards compatibility, but this lets you
select distinct on expressions and even multiple expressions, which
wasn't possible with the old column-name-only syntax...

            regards, tom lane