ITEC 3220 Lecture Notes - Lecture 1: Unique Key, Query Optimization, Relational Database
Document Summary
Relational data models, its based on relation not relation between object but as building construct. Relation is set of tubules meaning data items. Relation made of name and structure, a instance of relation has field access. We need to define field and attribute to describe real world objects. Structure consist of relation name, list of fields which will be associated with relation. Example employee id and last name, phone number of employee it will be by name. the order of name in relation schema is not important. We have to lease them one by one cant do the all at same time. Accessing field could be done by using their order. Schema example: book( price: decimal(5,2), title: char(50)) relation name is book then price and title will be columns which are data types ( not example of sql at this point, so its just basic idea of components)
