Re: join on next row

Harold,
That's brilliant.
Sim

Harald Fuchs wrote:
> In article <e780u8$1h5e$1(at)news(dot)hub(dot)org>,
> Sim Zacks <sim(at)compulab(dot)co(dot)il> writes:
>
>> I want my query resultset to be
>> Employee,EventDate(1),EventTime(1),EventType(1),EventTime(2),EventType(2)
>> Where Event(2) is the first event of the employee that took place
>> after the other event.
>
>> Example
>> EventID Employee EventDate EventTime EventType
>> 1 John 6/15/2006 7:00 A
>> 2 Frank 6/15/2006 7:15 B
>> 3 Frank 6/15/2006 7:17 C
>> 4 John 6/15/2006 7:20 C
>> 5 Frank 6/15/2006 7:25 D
>> 6 John 6/16/2006 7:00 A
>> 7 John 6/16/2006 8:30 R
>
>> Expected Results
>> John, 6/15/2006, 7:00, A, 7:20, C
>> Frank, 6/15/2006, 7:15, B, 7:17, C
>> Frank, 6/15/2006, 7:17, C, 7:25, D
>> John, 6/16/2006, 7:00, A, 8:30, R
>
>> To get this result set it would have to be an inner join on employee
>> and date where the second event time is greater then the first. But I
>> don't want the all of the records with a greater time, just the first
>> event after.
>
> You can filter the others out by an OUTER JOIN:
>
> SELECT e1.Employee, e1.EventDate,
> e1.EventTime, e1.EventType,
> e2.EventTime, e2.EventType
> FROM events e1
> JOIN events e2 ON e2.Employee = e1.Employee
> AND e2.EventDate = e1.EventDate
> AND e2.EventTime > e1.EventTime
> LEFT JOIN events e3 ON e3.Employee = e1.Employee
> AND e3.EventDate = e1.EventDate
> AND e3.EventTime > e1.EventTime
> AND e3.EventTime < e2.EventTime
> WHERE e3.EventID IS NULL
> ORDER BY e1.EventDate, e1.EventTime
>
>
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