Dutch version of this page

Below you will find (sorted alphabetically) additional pieces you can view with Adobe Acrobat Reader or download.

Attribute: Attribute name and Attribute value
(written in Dutch)
In the fourth edition of the book 'Databases en SQL' the concepts attribute name and attribute value are discussed. Previous editions did not discuss these concepts. The readers of these previous editions will find a definition of these concepts in this article. The application of these concepts is illustrated with examples.
File size is 51 KB. Written in Dutch.


Attribute or Attribute type
(written in Dutch)
The relational model of Codd uses the term attribute. The relational model uses this term for describing the type as well as for indicating the value collection at a certain moment in time. You can debate whether you should use the term attribute type instead of attribute. Some writers use the term attribute type.
In this article Ton de Rooij explains why he did not do this in the book 'Databases & SQL'.
File size is 51 kB. Written in Dutch.


Concepts: Transaction and Locking
(written in Dutch)
In the fourth edition of the book 'Databases en SQL' the database terms transaction and locking are added. Previous editions lack these terms. To be of service to readers of the previous editions Ton de Rooij explains these terms in this article.
Files size is 51 kB. Written in Dutch.


Book 'Databases en SQL': exercise material SQL
(written in Dutch)
In the book 'Databases en SQL' two databases are used for explaining the theory. You can download these databases here. In addition to that you can download an expanation about the use of these databases. You can also download a number of exercises. In the databases and in the exercises the names of columns are different for columns that have a # symbol in the name in the book. The # symbol is replaced by NR. The reason this has been done is that the use of the # symbol leads to problems in several database environments.

Access database
The tables of the two databases in the book 'Databases en SQL' you will find in the following Access database:
Access database with the databases of the book (625 kB)
(database data in Dutch)

Script for creating the databases
Those who have an Oracle, SQL-server, DB2, MySQL, PostgreSQL, SQLite3 et cetera database environment, can download here a script with which you can create the tables of the book in a database:
Script for making the tables (11 kB)
(written in Dutch)

Explanation of the use of Access and Oracle databases
The use of Access as a database environment is not that obvious. You cannot immediately start with the composition of a query. For this you first need to already have a query that you subsequently rewrite. For the trial of queries with Oracle you first need to execute the script after which you can use SQL Plus. For Access and Oracle you will find an explanation in the download:
The use of the databases in Access en Oracle (135 kB)
(written in Dutch)

Extra SQL exercises
Obviously you can use the queries in the book to exercise. However, it is probably nicer to have a few extra exercises. In the download you will find 32 exercises:
Exercises SQL (195 kB)
(written in Dutch)

workshop SQL
Not everybody succeeds in learning to make SQL queries by using the book. If you would like to attend a workshop, you may consider to attend one of the workshops Ton de Rooij lectures himself. The workshop is given in English. See the website of his company for subscribing:
Workshop SQL held in ENGLISH by Ton de Rooij


The use of DISTINCT in de SELECT-command
(written in Dutch)
When not all columns are included in a SELECT-command it is possible that the same line is multiple times part of the output of a query. This can be annoying. This can easily be avoided by the use of the phrase DISTINCT immediately behind SELECT. In this download Ton de Rooij shows in what ways DISTINCT can be used behind SELECT (starting with the fourth edition this explanation is part of the book 'Database en SQL'.
File size is 51 KB. Written in Dutch.


DISTINCT in the COUNT-functie
(written in Dutch)
When you apply the COUNT function to a column, the outcome is the number of rows in which a value for that column is present. If the same value is present in more than one row for that column, each occurrence of that value is part of the count. If you only want to count the number of different values you must use DISTINCT.
In the download Ton de Rooij explains this with examples (starting with the fourth edition this explanation is part of the text in the book 'Databases en SQL').
File size is 51 KB. Written in Dutch.


Embedded SQL
(written in Dutch)
If you want to use SQL statements in a 3GL program the compiler of the 3GL programming language needs to know which code is for the compiler and which code is for the SQL database environment. In addition to that a data exchange between the program and the database is needed. This is accomplished with variables. SQL must be able to see whether a variable is supplied by the 3GL program. For the use of SQL in a 3GL program you can use Embedded SQL language elements.
In the download an explanation is given of the most important language elements. A number of examples are given.
File size is 282 kB. Written in Dutch.


Applying the functions MIN and MAX on alphanumerical values
(written in Dutch)
In the book 'Databases en SQL' Ton de Rooij explains that the functions MIN, MAX, AVG and SUM are meant to be applied to numerical values. However, the functions MIN and MAX can also be applied to alphanumerical values. In the fourth edition of the book this is mentioned, but in this article Ton de Rooij explains this more extensively with the use of examples.
File size is 97 kB. Written in Dutch.


Information analysis using the ER-model
(written in Dutch)
The book 'Datamodellering' (data modeling) came out July 2010. The subject of the book is information analysis using the ER-model. It took (a long) time to write the book. To be of service to his readers, Ton de Rooij already had made a comprehensive explanation of information analysis using the ER-model. It is not a part of the book, but rather a text that is fully separate from it. The way the modeling is explained (in the download and the book) meets the way EXIN took exams in the modules HSB.1 (no longer in existance) and SIAA (structured information analysis advanced. The text of the download cannot supplant the book. Ton de Rooij strongly recommends you to buy the book 'Datamodellering' (if you can read Dutch).
File size is 124 kB. Written in Dutch.


Joins and Outer Joins
(written in Dutch)
In the book 'Databases en SQL' Ton de Rooij explains how you can make joins. In the first three editions of the book outer joins were not mentioned. In the more recent SQL syntax it is common to formulate inner joins, outer joins and cross joins. In the fourth edition outer joins and cross joins are discussed. For readers of the older editions Ton de Rooij explains in the article how to work with outer and cross joins.
File size is 56 kB. Written in Dutch.