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P1 The features of a relational database ++Databases are collections of data that are well organised, allowing them to be accessed and updated quickly and easily. There are different types of databases, classified by their content; they can be either bibliographic, text, statistical or multimedia databases. Some databases have their information split into several, more easily manageable groups, these are called relational databases. These separate tables can then be linked together, creating a relationship. Relational databases reduce data duplication, meaning the database will be smaller than if it was all lumped into a single flat file database.

Primary keys A primary key is a field in the table which enables you to see all the unique information that is in that table which will include numbers, transactional numbers and so on also they always tend to be at the top of the tables. For example in a school there will be the student/ teacher ID number and they will be most likely at the top of their tables. Also it can only be in one table but it can link to other tables to make it a record. Foreign keys A foreign key can be used to link the tables together and therefore a relationship of the tables is created. Also it is the field that is in one table is linked to a primary key in another table. In tables those that are identically named as fields and it is also known as foreign key.

Entities Entities are 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.

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.

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

P1 The features of a relational database

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 and 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: Aziz Surname: Ahmed Address: 73, High Street Postcode: CV34 5TR

Number and 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 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 One-to-One One-to-Many Many-to-Many this can be used for when you buy films because you as the 'one' and buy 'Many' tickets then it would be in the database. Another example to the 1-1 buying tickets for one family but booked the ticket in one name. An example of a one many relationship would be a car and its parts because a car cannot be a car without its parts and a many-many relationship example would be hotel

P1 The features of a relational database Normalisation Normalization is the process of efficiently organizing data in a database. There are two goals of the normalization process: eliminating redundant data for example storing the same data in more than one table and ensuring data needs make sense only storing related data in a table. Both of these are worthy goals as they reduce the amount of space a database consumes and ensure that data is logically stored.