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Logical Data Model

IT Notes → Database @ December 22, 2020

  • An entity type is any type of object that we wish to store data about.
  • A relationship type is a named association between entities.
  • Relation – A data object defined by a set of attributes. For example, “employee” is a relation with various attributes that define the employee data object. “Relation” is also called “table”.
  • Attribute – A kind of information that describes one aspect of a data object. For example, “age” is an attribute of a person, and “salary” is an attribute of an employee. “Attribute” is also called “column”.
  • Tuple – An instance of a data object with specific values for all attributes of the relation. For example, one tuple of the “course” relation is the operating system course with “operating system” as the value of the “course name” attribute, and other values for other attributes. “Tuple” is also called “row” or “record”.

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