1.3.2 a + b +c – Databases - DONE

An organised collection of data stored in tables.

A field is a column. It holds specific attributes.

A record is a row. It stores information about individual instances of the entity that the table represents.

An arrangement of data made up of columns called fields and rows called records. They represent an entity.

A database that stores data in a single table, often in a plain text file. Usually, each line will hold a single record and delimiters such as commas are used to separate this into different fields.

-They are easy to set up as only 1 table is needed -All records are stored in 1 place

-They can contain a lot of redundant data which increases the amount of storage space needed -Searching the database can be slower as there is more data to search than in a relational database -It can be difficult to manage and to expand

A database that stores data in multiple tables, These are linked together using relationships created by primary and foreign keys.

-There is less duplication of information, so less redundant data. This can reduce the file size. -They allow for complex queries to be performed -They improve the consistency of data -It can be more secure as the different tables allow for different users to have different access levels -The database is easier to manage and to expand. -Searching the database may be faster as there is less data as not all tables need to be searched.

-They are generally more difficult set up and more technical knowledge is required to do things such as normalisation -Data is spread out between multiple tables so some tables may be link tables which only display key fields / references -They are more expensive as you will need a database management system rather than just a basic text file.

A field that is unique

A field that links to a primary key in a second table. It doesn’t have to be unique and can appear multiple times in a table.

A additional or alternative key to allow unique identification of a record (not the primary key). It allows a database to be searched quickly as the database can be ordered and searched by the secondary key.

A composite key is a specific type of primary key which uses the contents of two or more fields from a table to create a unique value

They represent relationships. Each entity is represented as a box labelled with its name. Each entity is linked by lines. One line from / to an entity represents a ‘one’ side of a relationship. A three-pronged line to / from an entity represents a ‘many’ side relationship. These are used to showcase one-to-one, one-to-many and many-to-many relationships.

Indexing is a method used to store the position of each record ordered by a certain attribute. This is used to look up and access data quickly.

-Form -Optical Character Recognition (OCR) -Optical Mark recognition (OMR) -Sensors -Magnetic stripes -Chip and pin -Barcodes -QR codes

-Validation can be used to check for common errors such as duplicate values. -(If it’s electronic) Data can be entered directly into the database so limited manual processing is required -It can be done from a remote location

Technology that helps to automatically read text by interpreting the shape of letters. It works better with printed rather than handwritten text. It helps to speed up and automate data input.

It is used to input answers or marks made by a user, such as in multiple choice tests or on a lottery ticket. This is a fast and efficient way of collecting data and inputting it into a database while significantly reducing the possibility of human error.

-Structure Query Language (SQL) -Query by Example (QBE)

It’s a declarative language used to manipulate databases. It enables the creating, removing and updating of databases.

It’s a graphical query language which makes use of visual tables where the user can enter commands and conditions. Once a query is built using QBE, it’s converted into statements that can be executed against the database. A benefit of QBE against SQL is that the user doesn’t need to remember the finer details of SQL syntax.

They enable you to: -Specify tables -Specify fields -Specify criteria -Specify output sorting -Use boolean expressions