UNIT 18 P1- Explain the features of a relational database - ALL ASSIGNMENTS HERE!! PASS, MERITS AND DISTINCTIONS

UNIT 18 P1- Explain the features of a relational database 

ALL ASSIGNMENTS HERE!! PASS, MERITS AND DISTINCTIONS

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What is Relational Database?

Relational database eliminates the duplication of data. Instead of having all the needed information within one table, you would split up the table into information such as in a college data you would have a table with students names, age and addresses in a primary field i.e. student ID number. This field would then be linked to another table which would be enrolment as a student “enrols” onto a “course” which would then be connected on another table called “tutor” which would sort out the “room” they would be teaching in. Once a table is made it has to be linked to other tables to be made into a database; the database helps to maintain accuracy, availability, usability, resilience organisation and stop duplication from happening as it can be sieved out. Also the database can be used for storing managing and retrieving information.

The main features

When it comes to databases they have a number of main features which are made of customisable templates, calculated fields for powerful database application, integrated search, permission and access, mail merge, import/export between databases and apps, relational databases capability, customisable views and print reports, field types and integration. These features are highly beneficial for a database system because they are able to access the data needed quickly. There are also other main features that are very important to any database they are:

Entities/tables – the use of tables is to store data to be viewed at a later data if needed within the database. The data can be stored in countless amounts of tables and all databases can store a lot of tables.

Attributes/fields - a field that is made up of a piece of data/information inside a record which would be called a “record”.

Records – records contain different types of individual pieces of information which might consist of like first/last name, are, age and gender. This type of information is called a field.

Forms - The forms within a database is where you can input data in to. A benefit of using forms is to input data, which you can create restrictions which make sure only valid/relevant data is entered into the form.

Queries – They make finding the data you need incredibly easy.  They can be used to find a set of data defined by the user.

All of the examples above are ways a database can store, receive, send and search a specific data to another piece if the database system. Attributes play a big part of any database as it strengthens the storage of information held.

Data types

Databases are permanently kept as data to make sure that the data is more efficient and also the different types of data can normally be classed as a certain ‘data types’. The main data types are:

Text/alphanumeric - This refers to the data that is made up of letters and numbers. Also symbols and space may be allowed to be incorporated in.

Here is an example:

Forename: Tom

Surname: Ford

Address: 73, High Street

Postcode: CV34 5TR

Number/ numeric – This allows for a whole number or a decimal number to be use. Only numbers can be entered and not letters nor symbols.

Here is an example:

15

21.35

Currency – This automatically formats the data to have a £ or $ or Euro symbol in front of the data and also ensures there are two decimal places.

Here is an example:

£5.75

$54.99

Date/ time - This restricts data entry to 1-31 for day and 1-12 for month. It checks if the date actually exist. It formats the data into long, medium or short date/time.

Here is an example:

Long Date: 20 February 2006

Medium Date: 20-Feb-06

Short Date: 20/02/06

Long Time: 18:21:35

Medium Time: 06:21 PM

Short Time: 18:21

Boolean - Data is restricted to one of only two choices.

Here is an example:

Yes/No

Male/Female

Hot/Cold

Relationships

Relationships within a database are important as they keep tables connected to allow the database to work. The data is split up into sensible data groups, for instance student ID data, enrol data, course data, tutor data and room data, it then will be separated into a table where each of the categories will split into groups and once the tables are setup then the relationship will be able to be created to link all of them together. With relationships the main benefits of the database will that data doesn’t have to be duplicated but when a student enrols on to a course then a completely new record on the course table will appear and it will help to identify that student. To Reduce the data duplication lessens the risks of making mistakes because by every mistake that is made someone will have to retype every piece that was lost and while by doing that also causes a risk of misspelling happening while re-entering the database.

Data redundancy

The information that is used more than once in a table is called date redundancy. It is a condition that is created within a database or data storage in which the same piece of data is held in two different places. This can occur by accident, but is also done deliberately for backup and recovery purposes. You can avoid data redundancy by developing and organising different fields and tables within the database. To do this you could split the large tables into smaller ones and then defining the relationships of them. The job of it is to separate the data, which means any deletion of data, modifications and additions of fields.