Reverse a text in PostgreSQL

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dys on Friday, July 28. 2006:

Pavel Stehule on Wednesday, July 27. 2011:

Alexandr on Saturday, September 24. 2011:

Posted by Andreas 'ads' Scherbaum on Monday, July 24. 2006

I'm always searching for a reverse function, so here is the link:

http://www.varlena.com/GeneralBits/53.php

code snippet is available in plperl and plpgsql.

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Using recursion, one can also achieve it with a plain sql function: create function reverse(text) returns text as $$ select case when length($1)>0 then substring($1, length($1), 1) || reverse(substring($1, 1, length($1)-1)) else '' end $$ language sql immutable strict;

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a code from Varlena is not good - there is a few issues - first issue is using a WHILE statement. FOR statement is better - is faster. And you can use a simple and relative fast SQL function create or replace function rvrs(text) returns text as $$ select string_agg(substring($1 from i for 1),'') from generate_series(length($1),1,-1) g(i) $$ language sql;

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Here is one more function to reverse text that uses FOR statement if anybody interested. create or replace function rev(varchar) returns varchar as $$ declare _temp varchar; _count int; begin _temp := ''; for _count in reverse length($1)..1 loop _temp := _temp || substring($1 from _count for 1); end loop; return _temp; end; $$ language plpgsql immutable;

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February '23