First year

1. DATA PROCESSING
Data processing Þ any operation applied to data in order to
achieve a specific task: producing new data or reproducing the
existing data in an organised manner.
common data processing - operations imposed by the fact that
data must be stored on magnetic support and extracted from it
main data processing - operations that really process
data in order to satisfy user needs

2. Common data processing
Data storing
•collect data from user
•validate data (check data for errors and ask the user to correct the
mistakes he made)
•encode data
•organise data (group data on logical criteria, add identification
information for later retrieval and group data to meet external device
requirements - data clustering)
•write data on magnetic support

3. Common data processing
Data retrieving
•access data on magnetic support (using identification
information added when data is organised )
•read data from external support and store it in
internal memory
•decode data
•communicate data to the end user - write data on
output devices

4. Main data processing
in the process of data retrieving at the moment when
data are in the internal memory before communicating data to the end
user
at the access moment, considering the process of looking for
a precise data in a large collection on magnetic support
a complex activity - it doesn't process user data but auxiliary data that
refer to identification and organisation –
data querying.

5. Main data processing
Main data processing produce new data needed by
the end user on the basis of data stored in the
computer.
Þ the result of computations, of reordering, grouping or
summarising performed on existing data.
Þ complex operations that involve a lot of elementary
operations:
arithmetic operations: +, -, *, /, ­
logical operations: È, Ç, not
comparison operations: <, >, =, £, ³, ¹
strings operations (concatenate, split, merge, select)

6. PROGRAMMING
LANGUAGES
A program is a sequence of instructions telling the
computer what to do on data in order to achieve a
specific task.
An instruction is a command specifying the operation to be
done and the data that is involved in.
Physical instructions (machine code) are directly
performed by the computer.
Logical instructions - user-oriented and form the first
programming language – the assembly language.

7. PROGRAMMING
LANGUAGES
the data description - must specify the name, the type and
the size for memory variables and file name and record’s
structure (field name, type, size) for data stored on external
magnetic support.
the set of instructions designed to process data according
to an algorithm that express in logical form the user intention.
The algorithm presents the decomposition of the task in
activities, sub-activities up to operations that can be performed
by a single instruction

8. PROGRAMMING
LANGUAGES
A set of programs written to solve a business
problem form an application system.
Programming languages:
I generation: machine language
II generation: assembler languages
III generation : high-level instructions– procedural
(Cobol, Fortran, C , Pascal)
IV generation : declarative programs (SQL,QBE)
V generation : symbolic processing ( Prolog)

9. Application programming languages
PC software tools
RPG
SAS graph
Access, excel, …
SQL
Report generator
Graphics language
FOCUS, Front page
Application generator
APL, Nomad2
4th level
ERP
languages
COBOL, FORTRAN, BASIC, ALGOL, Pascal, ADA, C, C++, Visual Basic, JAVA
Assembly language
Machine code
ABAP (SAP), Poeple tools(Poeple soft),
Very high-level
Programming language
Query language
3rd
2nd
1st
End Users oriented IS professionals oriented

10. Historically,
1st GL was (and still is) a machine language based on
binary code.
2nd GL is assembly language (or assembler).
3rd GL are procedural language close enough to human language by using
some english
common words. So, it is a « high level » programming language.
As object oriented language, there are :
C++ is an object oriented version of C.
Java is also object oriented, but is very friendly to develop particular tasks
called « applets » for Web sites. They can be downloaded from a network,
can run on any computer and operating system.

11. 4th GL is a less procedural or at the limit nonprocedural programming
language which can be employed directly by end users or by less skilled
programmers to develop applications more rapidly than conventional
language.
There are different levels of 4th GL from no technical assistance for end
users to productivity enhancement of professional programmers.
5th GL is already used by some companies. It visuals programming
products for developing applications in Java, for example.
Visual programming allows to easily envision object-oriented programming
class hierarchies and drag icons to assemble program components

12. Data base approach
generalised programs - no more data dependent
half built programs that solve the common part of data
processing (data retrieval, sorting, grouping, summarising) and
enable the user to specify his particular computations or
layouts.
Þ declarative languages - tell the computer what to
do not how to do .
ßn
onprocedural, they are used to express the user
requests for data in a standardised manner.

13. Levels of data processing
elementary level - the simplest operations performed on the
smallest pieces of data: memory variables (or fields from files).
At this level data processing relays on machine oriented
operations (operations that are directly performed by the
logical and arithmetical unit of the computer).
record level - mainly input - output operations (write, read,
delete, update) performed on physical records - operations
related directly to common data processing

14. Levels of data processing
file level - user oriented operations performed on the
whole data collection in order to satisfy user requests.
These operations are the basis of main data processing,
performed in user benefit (data reordering, grouping, selecting,
merging, summarising, etc.).
Processing data at file level is influenced only by the way the
files are organised (independent or related)

15. FILE ORIENTED DATA
PROCESSING
Used mainly in relational data models and closely related with it
(relational data processing).
Data are stored in files record by record; data storage is
record oriented.
Data are retrieved as a whole; data retrieving is file
oriented.
File oriented data processing is done by elementary operations
similar to set operations called relational operators.

16. Relational operators
Þ basic data retrieval procedures that could be applied to a
file collection and produce a new file as result
If exists two tables then a generic operator combines them
producing a third table.
T1âT2 ® T3 binary operators
â T1 ® T2 unary operators – act on a single table
A file collection and the relational operators form
the relational algebra (algebraic structure).