Advantages And Disadvantages Of A Database

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What is a database?
A database contains a variety of data which are structurally placed in order. They can easily be manipulated, accessed and viewed e.g. a dictionary, timetable or telephone book. A database is like a bank, were you either retrieving the money as well as storing it or you just simply view the amount.
In this database what we can identify are the table, record, field and field value. Firstly the table also known as the File, highlighted in green this contains e.g. record of the entire patients. Moving on to the record which are placed in each row (in red) shows a gathering of data for a specific element. A field or column displayed in yellow is a particular element of data shared to all records. What is a relational database? …show more content…

the identical company address. To reduce or getting rid of duplicated data entry instead of typing the address all over again we can instead give it ID for instead ‘S01’ the ID will become the primary key in which we can identify each supplier by the ID. The advantages are that it will take less time to search it on the database in addition to a reduction in the amount of data being kept & input. Plus it could also guide the user in which e.g. selecting the right …show more content…

A simple primary key only contains one field only e.g. Student ID however for a composite primary key more than one field is necessary to find the precise value e.g. cars, the brand and the model of the car . There are many kinds of model for types of brand (Audi, BMW, Citroen, Ford and etc.) using composite primary key you can uniquely identify each car from the same brand in the database.
A table can have single or multiple foreign keys, a primary key and Foreign key are linked together to create a relationship between the tables (entities), this happens when both tables (and more) have found the same primary key. Both primary keys can’t have the same name so we call one of them a foreign key.
When a relationship is linked between two tables from a primary key to a foreign key, a referential integrity is necessary therefore that we can’t change any data from the foreign key (table) however only can change it in the primary key (table) to avoid any pointless

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