4.10 - Fundamentals of databases

Something used to represent an object in the real world that can be distinguished from other objects Can be a physical object (such as a person or a place) or a concept (such as an activity or a task) for which we need to record data in the database

Something used to represent a property, a quality or a characteristic that describes an entity E.g. the name of an employee, or the date and time that a booking was submitted

Entity identifier/key attribute - an attribute/set of attributes used to uniquely identify each instance of an entity Composite entity identifier - a set of the minimum number of possible key attributes combined together

One-to-one - whenoneinstance of an entity is associated withonly oneinstance of another entity E.g. each school is run by one head teacher One-to-many - whenoneinstance of an entity is associated withmore than one instance of another entity E.g. each student books many appointments Many-to-many - whenmore than one instance of an entity is associated withmore than one instance of another entity E.g. many students are taught by many teachers

A database where separate tables are made for each entity, and relationships between entities are represented by foreign keys

Primary key - a unique identifier that identifies each record in a table Composite primary key - a primary key made up from two or more other keys Foreign key - a linking attribute that joins two tables in a relational database by being a primary key in one and a foreign key in the other