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Date: Thu, 02 Jul 2009 17:39:27 +0200
From: Frank Lupo <frank_lupo@email.it>
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To: empire-db-dev@incubator.apache.org
Subject: reverse function in postgresql 
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Hi all,
in postgreql the reverse function not exist.
Is posible create function reverse when connect to db?

thanks

=====================================================
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;
         SELECT substring(original FROM mypos FOR 1) INTO onechar;
         reversed := reversed || onechar;
         mypos := mypos -1;
      END LOOP;
      RETURN reversed;
   END
' LANGUAGE plpgsql IMMUTABLE RETURNS NULL ON NULL INPUT;

=====================================================
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;
      SELECT substring(original FROM mypos FOR 1) INTO onechar;
      reversed := reversed || onechar;
      mypos := mypos -1;
    END LOOP;
    RETURN reversed;
  END
' LANGUAGE plpgsql IMMUTABLE RETURNS NULL ON NULL INPUT;
=====================================================
create or replace function reverse_string(text) returns text as
'
DECLARE
reversed_string text;
incoming alias for $1;

BEGIN

reversed_string = '''';

for i in reverse char_length(incoming)..1 loop
  reversed_string = reversed_string || substring(incoming from i for 1);
end loop;

return reversed_string;
END'
language plpgsql;


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