Re: [GENERAL] 'a' == 'a '

Dann Corbit wrote:
>> -----Original Message-----
>> From: Tom Lane [mailto:tgl(at)sss(dot)pgh(dot)pa(dot)us]
>> Sent: Thursday, October 20, 2005 2:54 PM
>> To: Dann Corbit
>> Cc: Richard_D_Levine(at)raytheon(dot)com; general(at)postgresql(dot)org; pgsql-
>> hackers(at)postgresql(dot)org Subject: Re: [GENERAL] [HACKERS] 'a' == 'a '
>>
>> "Dann Corbit" <DCorbit(at)connx(dot)com> writes:
>>> I guess that additional ambiguity arises if you add additional
>>> spaces to the end. Many database systems solve this by trimming
>>> the characters from the end of the string upon storage and the
>>> returned
> string will
> not
>>> have any trailing blanks.
>>
>> Can you document that? ISTM that that would effectively make char(n)
>> and varchar(n) exactly equivalent, which is ... um ... a bit stupid.
>
> This is SQL*Server:
>
> drop table test_char
> go
> create table test_char(
> fixed_30 char(30),
> varch_30 varchar(30),
> nchar_30 nchar(30),
> nvarc_30 nvarchar(30)
> )
> go
> insert into test_char values('Dann ', 'Dann ', 'Dann ', 'Dann ') go
> select len(fixed_30), len(varch_30), len(nchar_30), len(nvarc_30)
> from test_char go
>
> Result set:
> 4 4 4 4

For SQL Server, you are seeing the behaviour of the len function,
none of the data has been trimmed.
Using the same tables:

select len('x' + (fixed_30) + 'x'),
len('x' + varch_30 + 'x'),
len('x' + nchar_30 + 'x'),
len('x' + nvarc_30 + 'x')
from test_char

Result set :

32 7 32 7

Cheers, Kurt.

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