Resp.: difference between current_timestamp and now() in quotes

2009/1/22, Adrian Klaver <aklaver(at)comcast(dot)net>:
> On Thursday 22 January 2009 8:16:46 am Alvaro Herrera wrote:
>> Grzegorz Jaśkiewicz escribió:
>> > test2=# insert into dupa(a) select 'current_timestamp' from
>> > generate_series(1,100);
>> > ERROR: date/time value "current" is no longer supported
>> > LINE 1: insert into dupa(a) select 'current_timestamp' from generate...
>> > ^
>> > test2=# insert into dupa(a) select 'now()' from generate_series(1,100);
>> > INSERT 0 100
>> >
>> >
>> > Any ideas why the difference ?
>>
>> The parser handles CURRENT_TIMESTAMP (and others) specially, and doesn't
>> recognize it in quotes. I don't know why 'now()' works; I think it is a
>> literal of type unknown. I guess it's expanded to the actual value in
>> later parsing stages.
>>
>> --
>> Alvaro Herrera
>> http://www.CommandPrompt.com/
>> PostgreSQL Replication, Consulting, Custom Development, 24x7 support
>
> At least on 8.2 'now()' does not work either at least not in the way I
> think
> you want. I get:
>
> test=# SELECT 'now()';
> ?column?
> ----------
> now()
> (1 row)
>

Table 8-13. Special Date/Time Inputs
http://www.postgresql.org/docs/current/interactive/datatype-datetime.html

bdteste=# SELECT 'now'::date, 'yesterday'::date, 'today'::date,
'tomorrow'::date;
date | date | date | date
------------+------------+------------+------------
2009-01-22 | 2009-01-21 | 2009-01-22 | 2009-01-23
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