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* Re: Add: Special sort querstion
@ 2009-04-01 14:57 Dirk Jagdmann <jagdmann@gmail.com>
2 siblings, 0 replies; 3+ messages in thread
From: Dirk Jagdmann @ 2009-04-01 14:57 UTC (permalink / raw)
To: d.piekarski@vivawasser.de; +Cc: pgsql-sql
I think it can not be done with default PostgreSQL functions and
operators, because you must compare two different columns of two rows
depending which row is on either side of the "<" comparision.
But I think you can do this with the following steps:
1) create a new type as a 4-tupel of start_lat, end_lat, start_lng, end_lng.
2) write a comparison function for this type
3) write a SQL-Function to convert 4 values into your new type (for
example: ToMyType(start_lat, end_lat, start_lnd, end_lng) returns
MyType...)
4) use ToMyType in the order clause of your select
If this would work, I'm interested in a working example code :-)
--
---> Dirk Jagdmann
----> http://cubic.org/~doj
-----> http://llg.cubic.org
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Add: Special sort querstion
@ 2009-04-01 14:57 Dirk Jagdmann <jagdmann@gmail.com>
2 siblings, 0 replies; 3+ messages in thread
From: Dirk Jagdmann @ 2009-04-01 14:57 UTC (permalink / raw)
To: d.piekarski@vivawasser.de; +Cc: pgsql-sql
I think it can not be done with default PostgreSQL functions and
operators, because you must compare two different columns of two rows
depending which row is on either side of the "<" comparision.
But I think you can do this with the following steps:
1) create a new type as a 4-tupel of start_lat, end_lat, start_lng, end_lng.
2) write a comparison function for this type
3) write a SQL-Function to convert 4 values into your new type (for
example: ToMyType(start_lat, end_lat, start_lnd, end_lng) returns
MyType...)
4) use ToMyType in the order clause of your select
If this would work, I'm interested in a working example code :-)
--
---> Dirk Jagdmann
----> http://cubic.org/~doj
-----> http://llg.cubic.org
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Add: Special sort querstion
@ 2009-04-01 15:08 Scott Marlowe <scott.marlowe@gmail.com>
2 siblings, 0 replies; 3+ messages in thread
From: Scott Marlowe @ 2009-04-01 15:08 UTC (permalink / raw)
To: d.piekarski@vivawasser.de; +Cc: pgsql-sql
On Fri, Mar 27, 2009 at 6:10 AM, Dominik Piekarski
<d.piekarski@vivawasser.de> wrote:
> Oh, actually every row of the same id-range has the same start_lat/start_lng
> coordinates as the predecessors end_lat/end_lng coordinates. But the
> question remains the same. Is there a way to do something like ORDER BY
> (start_lat = end_lat AND start_lng = end_lng) ? Or maybe another way to
> achieve the same result?
Would something like
order by start_lat-endlat, start_lng-end_lng
OR
case when start_lat=end_lat AND start_lng=end_lng then 0 else 1 end
???
^ permalink raw reply [nested|flat] 3+ messages in thread
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2009-04-01 14:57 ` Dirk Jagdmann <jagdmann@gmail.com>
2009-04-01 14:57 ` Dirk Jagdmann <jagdmann@gmail.com>
2009-04-01 15:08 ` Scott Marlowe <scott.marlowe@gmail.com>
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