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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for December 28th, 2016

Firebird – date and time literals, conversion to ISO-8601 compatible strings

Posted by jpluimers on 2016/12/28

For my reference:

select 'Date literal values' as description
      , (cast('now' as timestamp)) as nowTimeStamp
      , (cast('today' as timestamp)) as todayTimeStamp
      , (cast('tomorrow' as timestamp)) as tomorrowTimeStamp
      , (cast('yesterday' as timestamp)) as yesterdayTimeStamp
      , cast(cast('Now' as date) as varchar(10)) as nowDateCast
      , replace(cast(cast('Now' as date) as varchar(10)), '-', '') nowDateIso8601
      , cast(cast('Now' as time) as varchar(13)) as nowTimeCast
      , replace(cast(cast('Now' as time) as varchar(13)), ':', '') nowTimeIso8601
      , cast(cast('Now' as timestamp) as varchar(24)) as nowTimeStampCast
      , substring(replace(replace(replace(cast(cast('Now' as timestamp) as varchar(24)), '-', '') , ' ', 'T'), ':', '') from 1 for 15) as nowTimeStampIso8601
from rdb$database 
;

Output and transposed output:

DESCRIPTION         NOWTIMESTAMP            TODAYTIMESTAMP          TOMORROWTIMESTAMP       YESTERDAYTIMESTAMP      NOWDATECAST NOWDATEISO8601 NOWTIMECAST   NOWTIMEISO8601 NOWTIMESTAMPCAST         NOWTIMESTAMPISO8601     
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Date literal values 3-8-2016 8:45:12        3-8-2016                4-8-2016                2-8-2016                2016-08-03  20160803       08:45:12.3860 084512.3860    2016-08-03 08:45:12.3860 20160803T084512         

DESCRIPTION             Date literal values
NOWTIMESTAMP            2016-08-03 8:45:12
TODAYTIMESTAMP          2016-08-03
TOMORROWTIMESTAMP       2016-08-04
YESTERDAYTIMESTAMP      2016-08-02
NOWDATECAST             2016-08-03
NOWDATEISO8601          20160803
NOWTIMECAST             08:45:12.3860
NOWTIMEISO8601          084512.3860
NOWTIMESTAMPCAST        2016-08-03 08:45:12.3860
NOWTIMESTAMPISO8601     20160803T084512

References:

–jeroen

Posted in Database Development, Development, Firebird | Leave a Comment »

The Eight Fallacies of Distributed Computing

Posted by jpluimers on 2016/12/28

Thanks James Gosling for writing this, and Kristian Köhntopp for pointing me to it:

The Eight Fallacies of
Distributed Computing

by Peter Deutsch

Essentially everyone, when they first build a distributed application, makes the following eight assumptions. All prove to be false in the long run and all cause big trouble and painful learning experiences.

1. The network is reliable
2. Latency is zero
3. Bandwidth is infinite
4. The network is secure
5. Topology doesn’t change
6. There is one administrator
7. Transport cost is zero
8. The network is homogeneous
For more details, read the article by Arnon Rotem-Gal-Oz

Summary of the full PDF paper

With almost 15 years since the fallacies were drafted and more than 40 years since we started building distributed systems – the characteristics and underlying problems of distributed systems remain pretty much the same. What is more alarming is that architects, designers and developers are still tempted to wave some of these problems off thinking technology solves everything.

Remember that (successful) applications evolve and grow so even if things look Ok for a while if you don’t pay attention to the issues covered by the fallacies they will rear their ugly head and bite you.

I hope that reading this paper both helped explain what the fallacies mean as well as provide some guidance on what to do to avoid their implications.

–jeroen

Posted in Development, Software Development | Leave a Comment »

 
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