substring problem

Hi,

Sh A Guru Prasad wrote, On 12/31/2003 11:00 AM:

select trn_id,substr(hoa_id,1,13) from tbill_master where
substr(hoa
_id,1,13)='2202031040006';
trn_id | substr
----------------+---------------
25001203000416 | 2202031040006
25001203000417 | 2202031040006
25001203000418 | 2202031040006
25001203000419 | 2202031040006
25001203000420 | 2202031040006
25001203000421 | 2202031040006
25001203000422 | 2202031040006
25001203000536 | 2202031040006

and
select trn_id,substr(hoa_id,0,14) from tbill_master where
substr(hoa
_id,0,14)='2202031040006';
trn_id | substr
----------------+---------------
25001203000416 | 2202031040006
25001203000417 | 2202031040006
25001203000418 | 2202031040006
25001203000419 | 2202031040006
25001203000420 | 2202031040006
25001203000421 | 2202031040006
25001203000422 | 2202031040006
25001203000536 | 2202031040006
both give the same result how? Is it query problem or
postgress substring problem please clarify.

why? it's ok. The first position in string is 1, but you can use 0,
-100, or whatever. The manual says:
"substring(string [from integer] [for integer])",as you see: from
integer, for integer.
SELECT substr('1234',-1,3); = 1
SELECT substr('1234',1,1); = 1

this is the expected behaviour.

C.

Sh A Guru Prasad <guru@ap.nic.in> writes:

[ substr(x,1,13) is the same as substr(x,0,14) ]

This is not a bug, this is per SQL99 spec.

regards, tom lane