Re: Please help me write a query

Got it:
SELECT state1, timestamp
FROM (SELECT state1, timestamp, lag(state1) OVER (ORDER BY timestamp)
FROM test) as foo
WHERE state1 != lag OR lag IS NULL
ORDER BY timestamp;
state1 | timestamp
--------+----------------------------
1 | now() - interval '12 hours'
2 | now() - interval '9 hours'
1 | now() - interval '8 hours'

Without lag IS NULL I miss the first row.

On Thu, May 27, 2010 at 11:44 AM, Nikolas Everett <nik9000(at)gmail(dot)com> wrote:

> The 10 and 11 hour interval are being skipped because I'm only interested
> in the transitions of state 1. State 1 only transitioned three times at now
> - 12, now - 9 and now - 8.
>
> The table has both transitions in it because I frequently care about them
> both together. I just don't in this case.
>
>
> On Thu, May 27, 2010 at 12:36 PM, Justin Graf <justin(at)magwerks(dot)com> wrote:
>
>> On 5/27/2010 9:45 AM, Nikolas Everett wrote:
>>
>> Sorry. Here is the setup:
>> CREATE TABLE test (id BIGSERIAL PRIMARY KEY, state1 INT NOT NULL, state2
>> INT NOT NULL, timestamp TIMESTAMP);
>> INSERT INTO test (state1, state2, timestamp) VALUES (1, 1, now() -
>> interval '12 hours');
>> INSERT INTO test (state1, state2, timestamp) VALUES (1, 2, now() -
>> interval '11 hours');
>> INSERT INTO test (state1, state2, timestamp) VALUES (1, 1, now() -
>> interval '10 hours');
>> INSERT INTO test (state1, state2, timestamp) VALUES (2, 1, now() -
>> interval '9 hours');
>> INSERT INTO test (state1, state2, timestamp) VALUES (1, 1, now() -
>> interval '8 hours');
>>
>>
>> I want to write a query that spits out:
>> state1 | timestamp
>> --------+----------------------------
>> 1 | now() - interval '12 hours'
>> 2 | now() - interval '9 hours'
>> 1 | now() - interval '8 hours'
>>
>>
>> Have a question what makes these values different other than the
>> timestamp???
>>
>>
>> 1, 1, now() - interval '12 hours'
>> *1, 1, now() - interval '10 hours'*
>>
>> The reason i ask, is because you show *1, 1, now() - interval '8 hours'*
>> in the desired output. What logic keeps the 8 hour and 12 hour but not the
>> 10hour interval???
>>
>> Its kinda hard to understand why the 10hour interval is being skipped???
>>
>>
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>