Обсуждение: setting select limit?

If a select is going to match 1000 records, but I only want to
select the first 25, I thought I could:

select * from table limit 25;

But I guess I can't. How do I limit the query? I've search
around with no results. Thanks.

You need v6.4.2-feature-patch which implement LIMIT option:

  LIMIT   This is a new option to the SELECT statement, telling
            the  database  that  only  some  of the rows selected
            should be returned in the result set.

            The added syntax of the LIMIT option is:

                SELECT ... [LIMIT {ALL | lim} [, off]];
            or
                SELECT ... [LIMIT {ALL | lim}] [OFFSET off];

            where lim is a positive integer  value  greater  than
            zero  and off is an integer value greater or equal to
            zero. Both values can be specified as Parameters when
            using the server programming interface (SPI). In this
            case, a zero value given in the argument for the  lim
            parameter means ALL.

 You can find it in patches directory

  Regards,

    Oleg

On Wed, 10 Feb 1999, Frank Morton wrote:

> Date: Wed, 10 Feb 1999 20:36:57 -0500
> From: Frank Morton <fmorton@base2inc.com>
> To: pgsql-sql@postgreSQL.org
> Subject: [SQL] setting select limit?
>
> If a select is going to match 1000 records, but I only want to
> select the first 25, I thought I could:
>
> select * from table limit 25;
>
> But I guess I can't. How do I limit the query? I've search
> around with no results. Thanks.
>
>
>
>

_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83

>
> If a select is going to match 1000 records, but I only want to
> select the first 25, I thought I could:
>
> select * from table limit 25;
>
> But I guess I can't. How do I limit the query? I've search
> around with no results. Thanks.

    Exactly that syntax is provided for v6.4 in the feature patch
    you find in the patches directory of the ftp server.  And  it
    will be in the standard distribution of v6.5.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#======================================== jwieck@debis.com (Jan Wieck) #

Hi,

> You need v6.4.2-feature-patch which implement LIMIT option:

Or alternatively if you can't or don't want to apply a patch, have a look at
the

SET QUERY_LIMIT TO x

in Postgres 6.4

Command: set
Description: set run-time environment
Syntax:
        SET DateStyle TO
'ISO'|'SQL'|'Postgres'|'European'|'US'|'NonEuropean'
set GEQO TO 'ON[=#]'|'OFF'
set R_PLANS TO 'ON'| 'OFF'
set QUERY_LIMIT TO #
function in postgres 6.4

Regards,

---[  Neil Burrows  ]-----------------------------------------------------
E-mail: neil.burrows@gssec.bt.co.uk             British Telecom Plc.
      : neil@pawprint.co.uk                     Glasgow Engineering Centre
Web   : http://www.remo.demon.co.uk/            Highburgh Rd.  Glasgow  UK
-----------< Any views expressed are not those of my employer >-----------

>
> Hi,
>
> > You need v6.4.2-feature-patch which implement LIMIT option:
>
> Or alternatively if you can't or don't want to apply a patch, have a look at
> the
>
> SET QUERY_LIMIT TO x
>
> in Postgres 6.4

    It  is  commented  out  by default (#ifdef QUERY_LIMIT) and I
    recommend NOT to enable it.

    The implementation  of  SET  QUERY_LIMIT  hat  unwanted  side
    effects. If during the execution of such a query functions or
    triggers get  invoked,  the  query  limit  also  affects  the
    execution  of  their  queries.  That could damage triggers or
    give unpredictable results on functions.

    I'll ensure that the SET QUERY_LIMIT code will be removed  in
    v6.5.


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#======================================== jwieck@debis.com (Jan Wieck) #