For each item below, specify whether the statement is true (T) or false (F). A Database Schema keeps the data in a database. Each Data Model is based on a Database Management System (DBMS). Oracle and MYSQL are two of the most popular Data Models. JDBC is a Data Manipulation Language (DML) developed for Java. Database Users may desire to perform conflicting operations at the same time. For example, in an Airline Reservation System, two on-line users may see the last empty seat while trying to reserve a seat on a flight. Security features of a DBMS prevents them from reserving the same seat, therefore avoiding inconsistent database states. In the Entity-Relationship Model (E-R), any distinguishable abstract or concrete thing is called an entity set/type. In the Entity-Relationship Model (E-R), an Attribute maps an entity to another entity (or a set of entities). A Relationship, on the other hand, maps an entity to a primitive value. "many to many" relationships in E-R map each instance (entity) of an entity set to a subset of instances (entities) of a second entity set, and map each instance (entity) of the second entity set to a subset of the instances (entities) of the first entity set. In the E-R model, for each relationship there is also an inverse relationship. Generalization ISA is the result of taking the union of two or more lower-level entity sets to produce a higher-level entity set. It emphasizes the difference. In the E-R Model, ISA is a special form of a Relationship. ISA relationship is fully functional from super-entity type to sub-entity type, and partially functional from sub- entity type to super entity type. In the Network Data Model, relationships between record types are implemented by means of Link Types. Since there can be only one Link Type between two Record Types, we do not need to name the Link Types. In the Hierarchical Data Model, AA and many-to-many Link Types are forbidden. In the Hierarchical Data Model, each Record Type has one Parent Record Type. In the Relational Data Model, the order of attributes is important.

For each item below, specify whether the statement is true (T) or false (F). A Database Schema keeps the data in a database. Each Data Model is based on a Database Management System (DBMS). Oracle and MYSQL are two of the most popular Data Models. JDBC is a Data Manipulation Language (DML) developed for Java. Database Users may desire to perform conflicting operations at the same time. For example, in an Airline Reservation System, two on-line users may see the last empty seat while trying to reserve a seat on a flight. Security features of a DBMS prevents them from reserving the same seat, therefore avoiding inconsistent database states. In the Entity-Relationship Model (E-R), any distinguishable abstract or concrete thing is called an entity set/type. In the Entity-Relationship Model (E-R), an Attribute maps an entity to another entity (or a set of entities). A Relationship, on the other hand, maps an entity to a primitive value. "many to many" relationships in E-R map each instance (entity) of an entity set to a subset of instances (entities) of a second entity set, and map each instance (entity) of the second entity set to a subset of the instances (entities) of the first entity set. In the E-R model, for each relationship there is also an inverse relationship. Generalization ISA is the result of taking the union of two or more lower-level entity sets to produce a higher-level entity set. It emphasizes the difference. In the E-R Model, ISA is a special form of a Relationship. ISA relationship is fully functional from super-entity type to sub-entity type, and partially functional from sub- entity type to super entity type. In the Network Data Model, relationships between record types are implemented by means of Link Types. Since there can be only one Link Type between two Record Types, we do not need to name the Link Types. In the Hierarchical Data Model, AA and many-to-many Link Types are forbidden. In the Hierarchical Data Model, each Record Type has one Parent Record Type. In the Relational Data Model, the order of attributes is important.

Database Systems: Design, Implementation, & Management

11th Edition

ISBN:9781285196145

Author:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Publisher:Steven, Steven Morris, Carlos Coronel, Carlos, Coronel, Carlos; Morris, Carlos Coronel and Steven Morris, Carlos Coronel; Steven Morris, Steven Morris; Carlos Coronel

Chapter10: Transaction Management And Concurrency Control

Section: Chapter Questions

Problem 1P

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