1. Database Management Systems (DBMS)
Data Handling Software
Database Management Systems (DBMS)

2. Paper Databases
A database is a collection of data or information which is held together in an organised or logical way. 
Databases can either be paper based or computerised.

4. Computerised Databases
You will come across computerised databases in every aspect of your life.
Here are some examples with which you will be familiar:
Search engines e.g. Google, Ask, Bing
School electronic registers
Library database
Shop stock control system
DVLC - stores details of all driver licences and car registrations

5. Specification
Candidates should be able to define a database as a large collection of data items and links between them, structured in such a way that allows it to be accessed by a number of different applications programs.

6. What You Need to Learn From This Lesson
Definition of a database
Advantages and disadvantages of a database approach over flat files
Database security
Hierarchy of passwords
Storage of data separate to programs

7. Key Words Fields Table Primary Key Record
Relational Database Management System (RDMS)
Query
Report

8. Table
Fields
Field Names

9. Primary Key

10. Definition of files, records and fields
A file
is a set of related records
e.g. a file of patients
A record
is a collection of data about a particular person, object or concept
e.g. the data about one patient
A field
is a subdivision of a record which holds a particular item of data with a given data type
e.g.
Medicine quantity (data type is number)
Patient name (data type is text)
Primary Key
field(s) to uniquely identify a record

11. Records

12. Primary Key

13. A TABLE is made up of RECORDS
RECORDS are made up of FIELDS
FIELDS are made up of CHARACTERS

14. File, records & fields Stock File Stock code: SP2544
Stock name: Timber door panel
Material: Pine
Size: x600mm
Quantity:
Stock code: RF4237
Stock name: Timber door panel
Material: Pine
Size: x600mm
Quantity:
Stock code: PY3746
Stock name: Timber door panel
Material: Pine
Size: x600mm
Quantity:
One stock record
Stock code: TM1253
Stock name: Timber door panel
Material: Pine
Size: x600mm
Quantity:
One
field

15. Databases & Database management software (DBMS)
A database is a collection
of tables and records
DBMS - database (management) software
Is a layer of software inserted between the different applications (programs) and this data.
It is responsible for the creation/maintenance/manipulation of the database

16. Flat File Databases
A flat-file database is a simple database that stores all data in a single table in one file
A flat-file database can be stored in a text file, such as a a Spreadsheet, or in a database file that contains one or more unrelated tables.

17. Flat File Advantages
Useful for simple lists:
Easy to create

18. Flat File Disadvantages
Large amounts of duplicated data
Difficult to update
If entries change all instances have to be updated
Security
All users have access to the same set of data

19. Relational Databases
The problems associated with flat files can be solved by moving some of the data out of the main table and accessing it when required
holds data in many tables of records which are linked by relationships.
A relationship is implemented through common fields held in the two tables
What's the problem?

20. Relational Database Advantages
Avoids data duplication (redundancy)
data stored once
linked by key fields
all data available via relational links in key fields
Ensures consistency of data of data to all users

21. Relational Database Advantages continued
Increased security - What makes databases secure?
Hierarchy of passwords ID
Authentication
Authorisation to files and processing
DBMS can check permissions Read only Write only etc. Users only allowed to view the data they are entitled to, so there is less risk of accidental or deliberate destruction.
Data integrity
It is possible to specify constraints on the data to ensure it is in the correct format and range.

22. Disadvantages of relational database vs. flat files
More complicated to design and create a relational database than a flat file system
More expensive because flat file system can by created simply using spreadsheet software where as a relational database needs to be created with a DBMS

23. Database Security
DBMS controls security access to different parts of the database
Each user is given appropriate access rights to the database appropriate to the type of user they are and their job

24. Searching for data with specific criteria.
Database Software
Features – Ability to:
Produce Queries
Searching for data with specific criteria.
e.g.: looking for customers who all live in a certain postcode to arrange delivery of shopping.
Produce Reports
Outputting information in a printed format. e.g.: Printing customer bills with data from the customer accounts.
Import/Export
Transferring data between software packages e.g.: Mail merge where data is exported from

25. Advantages/disadvantages of Database Software
Advantages of Relational Databases
Disadvantages of Relational Databases
Only have to enter data once
They are complex, difficult, and time-consuming to design
Files and tables are linked, and so means if the data is changed in one application, the rest of the database will automatically be updated for other applications
Damage to database affects virtually all of the application programmes
It is quick and easy to access information
Search criteria can be use, saved and modified
Initial training for programmers and users is needed and can be costly
Everyone uses the same data, and so the data is consistent
Validation checks can be performed
Ensures data integrity
The structure of the database can easily be changed

26. Database Software
A database is an organised collection of data or information.
Computerised databases can import or export information.
This needs to be done easily as different systems are often used and the data must be read the same each time.

27. Query
The whole point in storing data in a database is the fact that it is easy to perform searches to extract data.
One way of searching for that data would be performing a search using the tables in the database.
Another is using commands written in a language called Structured Query Language (SQL).

28. Reports
Databases can perform queries and produce the results in a report.
This is usually printed out and presented in such a way that it is easily understood – for e.g. graphs, charts, tables, etc.