Theory question 104
Database ManagementPaper 2, Section A: Essay
(a) Explain the following database management terms: (i) entities (ii) attributes; (iii) relationships. (b)(i) Define cardinality in database management. (ii) Mention three cardinality relationships in database management.
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(a)(i) An entity is a person, place, thing or event about which data is stored, e.g. a student (a table).
(ii) An attribute is a property that describes an entity, e.g. a student's name or date of birth (a field/column).
(iii) A relationship is a link between entities, e.g. a student registers for a course.
(b)(i) Cardinality is the number of instances of one entity that can be related to instances of another entity.
(ii) One-to-one (1:1); one-to-many (1:M); many-to-many (M:N).
Give a school example for each term.