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

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Archive for the ‘InterBase’ Category

SQL: “where not exists … having” formulation; anti-join alternative

Posted by jpluimers on 2018/06/26

I need to write up some notes, but there are some links that will help me:

It’s a question of readability. There is no difference in performance.
Old versions of SQL Server were silly enough to look up meta data, but not any more.


I am not considering NULL or “fun variants” which don’t seem intuitive to me.



The question popped up in comments just now. I researched the manuals of the most popular RDBMS:

A search on SO for code:"EXISTS (SELECT 1" yields 5,048 results.
A search on SO for code:"EXISTS (SELECT *" yields 5,154 results.
Updated links and counts 07.2015.

So SELECT * has the popular vote and the big commercial RDBMS on its side.
I find SELECT 1 more intuitive. It’s like saying “if at least one exists”.
Is SELECT * more intuitive?




Posted in Database Development, Development, Firebird, InterBase, MySQL, PostgreSQL, SQL, SQL Server | Leave a Comment »

Visual Representation of SQL Joins – CodeProject

Posted by jpluimers on 2017/08/02

I thought I posted a reference to this a long time ago, but didn’t.

It’s one of the things I show when explaining joins to people. Sometimes I need it myself too (:

The article explains these in greater detail:



  • the opposite of OUTER JOIN is empty set.

But the diagram is usually speaks for itself.


Source: Visual Representation of SQL Joins – CodeProject

Read the rest of this entry »

Posted in Access, Database Development, DB2, Development, Firebird, InterBase, MySQL, OracleDB, PostgreSQL, SQL, SQL Server | Leave a Comment »

Firebird: creating indices in scripts after checking for their existence

Posted by jpluimers on 2017/07/11

A few notes when making scripts that create indexes based if they do (not) exist (yet):


Read the rest of this entry »

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

How to speed up Count(*) in InterBase/Firebird – Stack Overflow

Posted by jpluimers on 2017/02/14

The drawback of how the multigenerational architecture is implemented:

Even when an index is available on the column or columns included in the COUNT, all records must be visited in order to see if they are visible under the current transaction isolation.

The benefits of the MGA (multi-generational architecture) having far less locking than other architectures means you need to be careful using the COUNT operator on large result-sets.

In many systems the exact result of a COUNT isn’t very important, so you can use the workaround referred from How to speed up Count(*) in Interbase/Firebird – Stack Overflow

See also:


via: Select count(*) is slow

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

Im memoriam: Gwan Tan, friend, Delphi, Firebird, EKON and Delphi-Tage supporter

Posted by jpluimers on 2016/07/11

Overlijdensbericht Swie Gwan Tan; Eindhovens Dagblad; 20160711

Overlijdensbericht Swie Gwan Tan Eindhovens Dagblad; 20160711

Last friday, my good friend Swie Gwan Tan suddenly passed away. Like most good friends, we didn’t see each other often enough, but when we did it always was like we had last seen each other the day before.

We first met ages ago at early BorCon and EKON conferences: I remember them: Gwan, a little chine guy and a really really tall guy (Edwin) on many conferences. It didn’t take long before we chatted and became friends. It must have been the mid 199os, not even sure which year.

Was it the way he was a people person and both Edwin and me very technical? Or he deep into the database side of things and Edwin/me on the Delphi (and later .NET) side? Or were it the long (usually nights) of discussing all sorts of topics (way beyond software development) with some moderate alcohol intake?

I’m still not sure why. These things happen. The beauty of friendships.

Of course I knew Gwan was ill. More than a decade ago walking became more difficult because of a progressive muscle disease that would not affect his heart. Over time he got bound to a wheel-chair. Somewhere in-between he got a heart condition too.

Gwan stayed imperturbable and optimistic. He was enjoying watching sports (Gwan was – despite living near Eindhoven – a huge fan of AJAX, Edwin of Feyenoord, I didn’t care about soccer at all: we had so much fun!) current affairs and movies keeping in touch with so many people. Irregularly he even managed to visit both German and soccer matches. It was so good to see how he enjoyed those. He was also a great family guy: organising events was his thing. His siblings, nephews and nieces always had a great time when meeting him. And then there were the yearly summer BBQ events in the party: awesome!

So it was only natural that – after we started cooperating with better office Germany – Gwan would organise the Dutch “Knowledge Days” events and the technical guys (usually Edwin and me from the Dutch side and Daniel Magin from better office Germany) would present the sessions.

When better office Germany got in trouble (long story) Gwan asked if I could financially help him to take a stake so at least the German personnel could be payed. We did, lost financially but earned life long friendships (and learned a thing or two on how banks operate).

One of the things with Gwan was that there never was a dull moment and always an opportunity to learn. Even from mistakes. Of course we had words once every now and then. But never a really big fight. I guess that’s part of a good friendship.

Another thing was the combination of being modest about himself and proud about others. For example he always proudly named one of his sisters” my little sister” as he was so fond of what she accomplished.

I vividly remember spring 2009 when – right after the Delphi Live 2009 conference – some USA friends, Edwin and me organised a surprise 50th birthday dinner party for Gwan. Despite his condition, Gwan was really happy that he made it to the conference. So having a party like that was a total blast.

He attended way more conferences and seminars than I did, especially an Germany. Unlike me, Gwan loved driving long distance. So he attended many Firebird, Delphi-Tage and other events I didn’t make it to. When I was at events, I could always spot Gwan with lots of people around him. usually near a bar (:

Around the time Gwan’s mom died about 3.5 months ago he spent some time in hospital to treat the edema that came with his muscle condition. It took a while, but the medicines worked, he attended the funeral and moved to an apartment with facilities for disabled and direct access to care.

Last week he had was hospitalised and his conditions worsened faster than anyone expected. Friday morning he quietly passed away. No more pain. No more sorrow.

Sadly we are left behind, but also pleased that his ordeal is over.

A dear, generous, modest and positive friend is gone.

Attending the funeral service

If you want to attend the funeral service, please let me know so I can inform the family of an attendance estimate.

The funeral service will be held on Thursday morning July 14 at 11:30 at this location (they begin 11:30 sharp, be early!):

Onze Lieve Vrouw Presentatiekerk AalstEindhovenseweg 63
5582 HP Aalst -Waalre
The Netherlands

Phone: +31 40 221 22 85 (preferably between 10:00 and 12:00)

The above catholic church is easy to find as it is right in the center of Aalst-Waalre (see the church icon on the map). They welcome everyone: non-catholics and atheist are equally welcome.

There are parking spots nearby on the south side of “de Leesakker” (right behind Greek restaurant Olympia) or in the street next to Restaurant Lugar (for both, see the P markings on the map).

To stay: look for Hotels near Aalst-Waalre. I can recommend the Van der Valk Hotel Eindhoven as Gwan and I have organised some workshops and seminars there.

Sending flowers

Gwan in 2010

Gwan in 2010

If you want to send flowers, make sure they arrive Wednesday afternoon July 13 at this funeral service:

Monuta Sol funeral service
attn. family of Swie Gwan Tan
Felix Timmermanslaan 2
5644 RN  Eindhoven
The Netherlands

Phone: +31 40 212 9800

Monday (today) opportunity to condole

Today, Monday July 11 there will be a brief opportunity to condole the family from 16:30 till 17:30 at this funeral service:

Monuta Sol funeral service
Felix Timmermanslaan 2
5644 RN  Eindhoven
The Netherlands

Phone: +31 40 212 9800

Dutch “overlijdensbericht”

Op 8 juli 2016 is onze lieve, gulle, dappere broer en oom overleden.

Swie Gwan Tan

* Eindhoven, 16 mei 1959           ✝ Veldhoven, 8 juli 2016

zoon van

Sing Liong Tan en Polly Tan-The

  • Voorschoten: Swie Tjiang en Ida
  • Waalre: Yu Kai
  • Voorschoten: Li Sha en Jordi
  • Amstelveen: Swie Han en Marion
  • Amsterdam: Li Mai en Derek; Yu Ri en Marre
  • Amsterdam: Ingkie en Loes
  • Parijs: Xiu Lin en Bart; Qi Bo, Qi Mo, Qi San

Monuta Sol, t.a.v. familie Tan
Felix Timmermanslaan 2, 5644 RN  Eindhoven

De uitvaartdienst wordt gehouden op donderdag 14 juli a.s. om 11:30 uur in de Onze Lieve Vrouw Presentatiekerk, aan de Eindhovenseweg 63 te Waalre.

Later die dag brengen we Gwan in besloten krijg naar het crematorium te Heeze

Indien U geen persoonlijk bericht heeft ontvangen, gelieve deze aankondiging als zodanig te beschouwen.

English translation:

On July 8, 2016, our dear, generous, brave brother and uncle deceased.

Swie Gwan Tan

* Eindhoven, May 16, 1959           ✝ Veldhoven, July 8, 2016

son of

Sing Liong Tan and Polly Tan-The

  • Voorschoten: Swie Tjiang en Ida
  • Waalre: Yu Kai
  • Voorschoten: Li Sha en Jordi
  • Amstelveen: Swie Han en Marion
  • Amsterdam: Li Mai en Derek; Yu Ri en Marre
  • Amsterdam: Ingkie en Loes
  • Parijs: Xiu Lin en Bart; Qi Bo, Qi Mo, Qi San

Mailing address:
Monuta Sol funeral service
attn. Tan family
Felix Timmermanslaan 2
5644 RN  Eindhoven
The Netherlands

The funeral service will be held on Thursday, July 14 a.s. at 11:30 pm in the Onze Lieve Vrouw Presentatiekerk, Eindhovenseweg 63 Waalre.

Later that day we will privately bring over Gwan to the cremation center in Heeze.


Posted in About, Database Development, DB2, Delphi, Development, Firebird, History, InterBase, Personal, Software Development | 5 Comments »

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