1. Database Systems
Unit 16

2. What is a Database? Databases are everywhere! Student records
Mobile phone call records
Supermarket stock records
Why use a database?
Word Processors are used to process text
Spreadsheets are used to process numbers
What do databases process?
What is data?
Database Structure Presentation Unit 16

3. What is a Database A database is a collection of data
Database Management Software (DBMS) is the application that creates and accesses the database
Common DBMS include:
Microsoft Access
Oracle
MySQL
Databases store data in a structured way
Database Structure Presentation Unit 16

4. Database Structure
Databases are divided into tables so all the data about a certain thing (student, telephone call, stock item) is stored together
Tables are further sub-divided into fields, which set the structure of a table by defining the data items to be stored
Each table has a number of Records. Each record describes one ‘thing’ with values for each of the fields
What are the benefits of storing data in a structure like this?
Database Structure Presentation Unit 16

5. Primary Key
One field within each table is normally chosen to be the primary key
Unique identifier for each record
Usually a numeric or alphanumeric code
Ensures each record can be uniquely identified
Additional keys can be defined to speed up searching for records in a large database
Database Structure Presentation Unit 16

6. Database Objects Tables – store the data itself
Queries – used to answer questions about the data. Can extract records which match certain criteria
Reports – used to format the output of data from tables or queries in a user friendly way – mainly for printing.
Forms – used to input and/or output data in a user friendly way – for on-screen use
Database Structure Presentation Unit 16

7. Database Advantages Compared to a paper based filing system:
Creating and inserting records is quicker
You can sort the records in any order
Records can be found quickly, searches can be done on any field
Amendments can be easily done
Space required is much less
Data is more easily shared
Compiling reports which draw data from many records is much easier
Database Structure Presentation Unit 16

8. Database Advantages Compared to other software (e.g. Spreadsheet)
Can create multiple related tables (not covered in this unit)
Designed for large, multi-user databases
Searches can be more complex and can be saved (queries)
Can create reports and forms
Can create complete end user applications
Database Structure Presentation Unit 16

9. Database Disadvantages
Database software can be quite expensive, complex to understand and difficult to learn how to use.
Large multi-user databases require high performance hardware and expert technical support
Databases need to be carefully designed in order to provide the required functionality and performance
Care must be taken to ensure that the data that is put into the database is correct.
If the database stores data about real people then it must be registered with the Data Protection Act and its requirements must be complied with.
Database Structure Presentation Unit 16