'Candidate key' diaporamas de présentation

Prof. Sin-Min Lee

Final Revision 3. CS 157B Lecture 23. Prof. Sin-Min Lee. Modeling. A database can be modeled as: a collection of entities, relationship among entities. An entity is an object that exists and is distinguishable from other objects. Example: specific person, company, event, plant

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Chapter 6: Entity-Relationship Model

Chapter 6: Entity-Relationship Model. Chapter 6: Entity-Relationship Model. Design Process Modeling Constraints E-R Diagram Design Issues Weak Entity Sets Extended E-R Features Design of the Bank Database Reduction to Relation Schemas Database Design UML. Modeling.

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CMPT 354

SQL Constraints and Triggers. CMPT 354. SQL Constraints. Constraints Primary Key Foreign Key General table constraints Domain constraints Assertions Triggers. Bank ERD. Customer. Account. Branch. works. owns. holds. transacts. Transaction. Employee. osin. lname. fname. age.

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Lecture #2 ER-Model and The Relational Model

Lecture #2 ER-Model and The Relational Model. Agenda. Previous Lecture The Entity-Relationship Model The Relational Model. In the Previous lecture. We found that: What is the Database Management System (DBMS ) File Systems versus a DBMS Advantages of a DBMS Structure of a DBMS.

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Functional Dependencies and Normalization

Functional Dependencies and Normalization. Instructor: Mohamed Eltabakh meltabakh@cs.wpi.edu. What to Cover. Functional Dependencies (FDs) Closure of Functional Dependencies Lossy & Lossless Decomposition Normalization. Normalization. First Normal Form (1NF)

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The Relational Model

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Chapter 6: Entity-Relationship Model (part I)

Chapter 6: Entity-Relationship Model (part I). Modeling. A database can be modeled as: a collection of entities, relationship among entities. An entity is an object that exists and is distinguishable from other objects. Example: specific person, company, event, plant

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Decomposition, 3NF, BCNF

Decomposition, 3NF, BCNF. Decomposition of a Relation Schema. If a relation is not in a desired normal form, it can be decomposed into multiple relations that each are in that normal form.

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NOrmalization

NOrmalization. By: Shiraj Mohamed M | MIS | SEUSL. Normalization. Basically, normalization is the process of structuring the tables in a database for maximum efficiency

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The Relational Model and Relational Algebra

The Relational Model and Relational Algebra. Nothing is so practical as a good theory Kurt Lewin, 1945. The relational model. Overcame shortcomings of earlier database models Has a strong theoretical base Codd was the major developer. Problems with other models.

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CIS 5371 Cryptography

CIS 5371 Cryptography. 5b. Pseudorandom Objects in Practice Block Ciphers-. DES. DES is a special type of iterated cipher based on the Feistel network . Block length 64 bits Key length 56 bits Ciphertext length 64 bits. DES. The round function is:

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Chapter 8 Normal Forms Based on Functional Dependencies

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Functional Dependency

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Functional Dependency

Functional Dependency. Rajhdeep Jandir. Definition. A functional dependency is defined as a constraint between two sets of attributes in a relation from a database.

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Entity Relationship Diagrams

Entity Relationship Diagrams. Basic Elements and Rules. Introduction to Entity-Relationship (E-R) Modeling. Notation uses three main constructs Data entities Relationships Attributes Entity-Relationship (E-R) Diagram

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Normal Forms in Relational Databases 1

Normal Forms in Relational Databases 1. 1 Bolstad, P. pp 283-291. Problem. Massive tables with information about multiple entities become unwieldy making data update and maintenance difficult. They suffer from performance issues, consistency, and redundancy. Problem.

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Functional Dependence

Functional Dependence. In a relation including attribute A and B, B is functional dependent on A if, for every valid occurrence, the value A determines the value B An occurrence can not be used to show that a dependency is true, only that it is false A and B can be composite

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Advanced SQL

Advanced SQL. Murat Kantarcioglu Adapted from Silberchatz et al. slides. NULL Values. It is possible for tuples to have a null value, denoted by null , for some of their attributes null signifies an unknown value or that a value does not exist.

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Mapping ER to Relational Model

Mapping ER to Relational Model. Each strong entity set becomes a table. Each weak entity set also becomes a table by adding primary key of owner entity set. To create a table for an entity set: Non-composite, single-valued attributes become attributes of the table.

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