1. Introduction to Database systems
Week 2

2. What is a database?
A base of data, collected in some sort of a file system
Flat-file
Text file
Comma Seperated (CSV)
XML - formats
Code files
Books
Advanced filecollections
Spreadsheet
DBMS filesystems

3. Textbased command system
What is a DBMS?
Database management system
Textbased command system
- Ability to provide advanced interaction of data
- Manages users
- Manages access
- Manages rules
- Manages events
- Security
And a lot more
Database manager UI
Service setup UI
Advanced reporting UI
Programs
Services
File formats
Event management
Linking services
Broadcasting
Proprietary system of storing data

4. The landscape of databases
Vendor
Major DBMS
Minor DBMS
Microsoft
SQL server
Access / SQL server express (free)
Oracle
OracleDB ?
IBM
DB2
MySQL (oracle)
MySQL (free?)
MySQL (free)
Free versions usually have limitations built in!
There are other DB-systems and vendors out there!

5. What is data?
A piece of information, which cannot hold more than one meaning
Examples:
Name
Age
Street
City
economic numbers

6. What is data? Redundancy Inconsistency - Concurrency issues
Name
Postalnr
City
Jens
7100
Vejle
Lotte
Hanne
6000
Kolding
Børge
Name
Postalnr
City
Jens
6000
Vejle
7100
Hanne
6200
Aabenraa
Børge
6400
Sønderborg
- Error prone
- Time waste
- Concurrency issues

7. Exercise Can redundancy be a good thing?
Is there any form of data where its a good thing to have redundant but concurrent databases?
Sure they hold same versions of data!

8. What is Metadata? Examples Maximum length Text No text Between values
Data that describes the properties and expectations towards data
Examples
Maximum length
Text
No text
Between values
Must be filled

9. Exercise
Name
Age
Birtday
Address
Possible metadata ?

10. Types of database usage (academic)
Single user / desktop
Desktop programs
Online and nonline games
Multiuser
Services x programs at any time
Online games
Centralised vs. Distributed
Operational / production database
Economic data
DB for industrial production
Banking databases
Historical database
Old data kept for warehouse purposes
Data warehouse
Statistical collections
Strategic data

11. A bit about ORM´s Object relation management Problem!
Creating code to handle getting data to and from a database is cumberson and timeconsuming
Solutions!
Automation via metadata-mapping
More or less automation of CRUD operations
Create Read Update Delete

12. Elements of a database Data Typical valuetypes of data (name may vary)
Text – variable length of characters
Integer – a number with no , or . separation (whole number)
Decimal – a number with room for , or . separation

13. Elements of a database Table Column Column / domain xyz Row / Tuple
Field / datafield
Data in field
Table
A set of data from a row together = record

14. Elements of a database File Physical file (server)
The actual bunch of 0 and 1 on the harddrive
Virtual file (server / app)
A file that only exist in the RAM
Dataset (app)
A virtual file consisting of tables
Table (server / app)
A collection of rows/records of data

15. Elements of a database server
A server can mean different things
Physical machine
You can touch this
Virtual machine
OS instances living in RAM
Software
Instances of programs living in RAM