'Hourly emps' presentation slideshows

Conceptual Design Using the Entity-Relationship (ER) Model

672 views • 58 slides

The Evils of Redundancy

The Evils of Redundancy. Redundancy is at the root of several problems associated with relational schemas: redundant storage, insert/delete/update anomalies

670 views • 47 slides

The Entity-Relationship Model To Relational Model

The Entity-Relationship Model To Relational Model. Relationship Example. since. name. dname. psrn. budget. dob. did. Works_In. Employees. Departments. Relationship Sets to Tables. In translating a relationship set to a relation, attributes of the relation must include:

534 views • 29 slides

ICS 321 Fall 2009 The Relational Model (ii)

ICS 321 Fall 2009 The Relational Model (ii). Asst. Prof. Lipyeow Lim Information and Computer Science Department University of Hawaii at Manoa. Integrity Constraints (ICs). IC: condition that must be true for any instance of the database; e.g., domain constraints.

328 views • 24 slides

The Entity-Relationship Model

The Entity-Relationship Model. Chapter 2. name. ssn. lot. Employees. ER Model Basics. Entity : Real-world object distinguishable from other objects. An entity is described (in DB) using a set of attributes . Entity Set : A collection of similar entities. E.g., all employees.

361 views • 20 slides

Announcements

271 views • 12 slides

ER to Relational Mapping

ER to Relational Mapping. name. ssn. lot. Employees. Logical DB Design: ER to Relational. Entity sets to tables. CREATE TABLE Employees (ssn CHAR (11), name CHAR (20), lot INTEGER , PRIMARY KEY (ssn) ).

206 views • 12 slides

Decompositions

Decompositions. Given a relation schema R that is not in 3NF (or perhaps BCNF) decomposition can be used to help fix this problem Decomposition replaces R with R1,...,RN where 1) attributes of Ri are a subset of the attributes of R 2) each attribute of R is in at least one Ri

282 views • 10 slides

ICS 321 Spring 2011 Normal Forms 1

ICS 321 Spring 2011 Normal Forms 1. Asst. Prof. Lipyeow Lim Information & Computer Science Department University of Hawaii at Manoa. The Problem with Redundancy. Hourly_Emps. Suppose hourly wages are determined by rating Redundant storage : (8,10) stored multiple times

218 views • 9 slides