Re: Select latest Timestamp values with group by

Any update on the below query :-
I tried the below query but :-
*
select bb_id,lat,lon,max(dt_stamp) from gps_tracker group by bb_id;
*
ERROR: column "gps_tracker.lat" must appear in the GROUP BY clause or
be used in an aggregate function
LINE 1: select bb_id,lat,lon,max(dt_stamp) from gps_tracker group by...
^

********** Error **********

ERROR: column "gps_tracker.lat" must appear in the GROUP BY clause or be
used in an aggregate function
SQL state: 42803
Character: 14

I think this can be solved by applying some function to lat lon values
of max(dt_stamp) row.

Thanks

Adarsh Sharma wrote:
> Hi Craig :-
>
> Below is the schema of my table :-
>
> CREATE TABLE demo_table
> (
> id character varying NOT NULL,
> lat double precision,
> lon double precision,
> speed double precision,
> dt_stamp timestamp without time zone DEFAULT now(),
> CONSTRAINT gps_tracker_pkey PRIMARY KEY (id)
> )
> WITH (
> OIDS=FALSE);
>
> I let u know after some work on Window functions
>
> Thanks
> Craig Ringer wrote:
>> On 10/10/2011 08:32 PM, Adarsh Sharma wrote:
>>> Dear all,
>>>
>>> I need to write a query to select latest rows with timestamp values.
>>> My ID is repeated with lat lon and timestamp. I want the latest row of
>>> each ID ( group by id ).
>>
>> [snip]
>>
>>> "3911";"661000212";26.8491101532852;92.8058205131302;0;"2011-10-14
>>> 12:47:33.360572"
>>>
>>>
>>> Can anyone let me know the query for that.
>>
>> No, they can't. You only posted semicolon-separated data, not a
>> schema with column names or anything much else.
>>
>> For a task like this you can use a window function, or you can
>> self-join and use a WHERE clause to match the greatest row. Using a
>> window function will be MUCH more efficient, so only use the
>> self-join if you're running on a really old version of PostgreSQL.
>>
>> http://www.postgresql.org/docs/9.0/static/tutorial-window.html
>> http://www.postgresql.org/docs/9.0/static/functions-window.html
>>
>> Using the first_value or last_value window functions with an ordering
>> clause to select the greatest timestamp within each window frame.
>>
>> http://www.postgresql.org/docs/9.0/static/functions-window.html#FUNCTIONS-WINDOW-TABLE
>>
>>
>> --
>> Craig Ringer
>
>