Database basic
As I had a job interview position called 'data admin', I reviewed what I had studied from Univ. Entity Relationship Modelling : is a set of diagrammatic standards for depicting both the logical and physical structure of a database system P.Chen 1976 first proposed E-R models E-R Modelling symbols : Entities, Relationships, Attributes Entities :an entity is a thing, which is recognisable as being capabl of an independent existence, and may be uniquely identified, this definition allows for both physical objects(person, car, house) and events (a meetings, loans). - the names of entities must be in the singular as it refers to a single instance (in relationship terms) Relationships : a specific line between two entities and indicates that the primary key of one entity is a foreign key in the other One to One : signifies that for each instance of entity A there is one related instance of entity B. it is not often used or seen in full-scale relationship databases