Database Design
Database Design
Scenario
Currently a school uses a non-computerised database system to store the following information about its students: roll class, surname, first name, guardian 's name, address, student 's date of birth, gender, sport house, emergency-contact telephone number, mailing name, list of subjects offered, and subjects in which the student is enrolled. The system takes up a large amount of space, has many duplicated entries some of these with mistakes and it is time consuming to search. The school intends to introduce a relational-database management system to overcome these problems.
Current school data storage and retrieval system (the pre-computer database system)
h School staff, teachers and office staff are the users of the database.
h Database used to track all details of students in the school.
h Large amounts of data are stored. An individual record is required for each student.
h Lots of duplication exists as details of subjects offered by the school are duplicated on individual student records.
h Data is organised in alphabetical order on student names within years.
h Data is stored in a number of filing cabinets.
Advantages
h quick to find details of a student if year and surname are known
h data is stored in a central secure location
h original source material is stored in the student file.
Disadvantages
h slow to find details of students when surname and year are not known
h data storage takes up a lot of room
h minimal number of staff can access records at one time
h data is duplicated.
Stages of development of the computerised relational database system
The new computerised relational database system will be developed in the following stages:
h analysis
h design
h implementation
h maintenance
Analysis
In this stage the current system is analysed to determine the functions it performs and those that it is unable to perform. Direct and indirect users of the new
Scenario
Currently a school uses a non-computerised database system to store the following information about its students: roll class, surname, first name, guardian 's name, address, student 's date of birth, gender, sport house, emergency-contact telephone number, mailing name, list of subjects offered, and subjects in which the student is enrolled. The system takes up a large amount of space, has many duplicated entries some of these with mistakes and it is time consuming to search. The school intends to introduce a relational-database management system to overcome these problems.
Current school data storage and retrieval system (the pre-computer database system)
h School staff, teachers and office staff are the users of the database.
h Database used to track all details of students in the school.
h Large amounts of data are stored. An individual record is required for each student.
h Lots of duplication exists as details of subjects offered by the school are duplicated on individual student records.
h Data is organised in alphabetical order on student names within years.
h Data is stored in a number of filing cabinets.
Advantages
h quick to find details of a student if year and surname are known
h data is stored in a central secure location
h original source material is stored in the student file.
Disadvantages
h slow to find details of students when surname and year are not known
h data storage takes up a lot of room
h minimal number of staff can access records at one time
h data is duplicated.
Stages of development of the computerised relational database system
The new computerised relational database system will be developed in the following stages:
h analysis
h design
h implementation
h maintenance
Analysis
In this stage the current system is analysed to determine the functions it performs and those that it is unable to perform. Direct and indirect users of the new