Обсуждение: Equivalent of Reverse() functions

Kumar wrote:
> I am migrating an SQL Server 2000 database to Postgres 7.3.4 running
> on RH Linux 7.2. While migrating I encounter SQL Server REVERSE( )
> function, seems no such functions at Postgres.
> 
> Is there a equivalent function available at Postgres? Please shed
> some light

How about:

create or replace function reverse(text) returns text as ' return reverse($_[0]);
' language plperl;

regression=# select reverse('abcdef'); reverse
--------- fedcba
(1 row)

Joe

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> I am migrating an SQL Server 2000 database to Postgres 7.3.4 running
> on RH Linux 7.2. While migrating I encounter SQL Server REVERSE( )
> function, seems no such functions at Postgres.
>
> Is there a equivalent function available at Postgres? Please
> shed some light
No. If you have plperl installed, as somebody already posted, you can
take advantage of perl's built in reverse() function. Here is a
plpgsql version: 
CREATE OR REPLACE FUNCTION reverse(TEXT) RETURNS TEXT AS ' DECLARE   original ALIAS FOR $1;   reversed TEXT := \'\';
onechar VARCHAR;   mypos    INTEGER; BEGIN   SELECT LENGTH(original) INTO mypos;   LOOP     EXIT WHEN mypos < 1;
SELECTsubstring(original FROM mypos FOR 1) INTO onechar;     reversed := reversed || onechar;     mypos := mypos -1;
ENDLOOP;   RETURN reversed; END
 
' LANGUAGE plpgsql IMMUTABLE RETURNS NULL ON NULL INPUT; 
pg=> SELECT reverse('A man, a plan, a canal, Panama');           reverse
- --------------------------------amanap ,lanac a ,nalp a ,nam A
- --
Greg Sabino Mullane greg@turnstep.com
PGP Key: 0x14964AC8 200311291246
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