Transcript Tutorial 2
COMPSCI 280 Tutorial 2 Agenda • Views vs Tables • Characteristics of each • When to use each. • Exercises to illustrate concepts discussed. • Altering tables and records. • Exercises. Views • Stored on disk as query • Storage space is constant w.r.t. number of records. • Is Dynamic. • Data is can be changed. • Allows for more granular control of data that can be modified by users. • Query is executed to generate result set when data on view is requested. Tables • Stored on disk as records. • Memory required scales linearly with number of records. • Static in nature(until modified directly). • Data is tied to the table. • Less Granular Write permissions. Don’t use tables to • Repeat popular and complex queries. • Trying to handle granular security permissions. • Trying to ensure that information suit’s a particular audience. Use a view when: • More granular read/write permission is required. • You are working with already existent information. • You are trying to present already existent information to an audience in a particular way. • You are working with multiple tables and want to make future retrieval of the same complex query in future more efficient(indexing). • Hiding database specific stuff from end-user. • Dealing with information that is dynamic. Don’t use views when • Updating records. • Don’t cascade views ie. Views of views of views(very inefficient). Use a table when: • To store new information in a database. • To retrieve information as is from a table. How do they depend on each other? • They don’t in a sense. • They are designed independently of each other. • Tables are designed for ‘efficiency’. • Views are designed for ‘prettiness’. Any Questions???