bug in substring??? - Mailing list pgsql-hackers

From scott.marlowe
Subject bug in substring???
Date
Msg-id Pine.LNX.4.33.0402061419460.6661-100000@css120.ihs.com
Whole thread Raw
Responses Re: bug in substring???  (Joe Conway <mail@joeconway.com>)
List pgsql-hackers
I'm using substring.  Since I'm a coder more than a database guy, I 
expected this:

select substring('abcdefgh',0,4);

would give me 

abcd

but it gives me a left aligned 'abc'

select substring('abcdefgh',1,4);

works fine.

select substring('abcdefgh',-4,4);

gives me nothing.  Shouldn't a negative offset, or even 0 offset result in 
an error or something here?  Or is there a special meaning to a negative 
offset I'm not getting?

Just wondering.  





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