DATA MODELING & THE ENTITY-RELATIONSHIP MODEL

DATA MODELING & THE ENTITY-RELATIONSHIP MODEL Database Development Process - Consists of three major stages: requirements analysis, component design, and implementation. What is the Requirement Analysis stage also referred to as? - Requirements Stage What happens in the Requirements Stage? - System users are interviewed and sample forms, reports, queries, and descriptions of update activities are obtained. What is the information, obtained in the Requirements Stage, used for? - To create a Data Model. What is a Data Model? - A representation of the content, relationships, and constraints of the data needed to support the requirements. What is the Component Design Stage also referred to as? - System Design Stage and the Design Stage What happens during the Design Stage? - The data model is transformed into a database design. What does the database design consist of? - Tables, relationships, and constraints, consisting of table names, table column names, data types and properties of the columns, and a description of primary and foreign keys. What do the constraints consist of, in design stage? - Limits on data values, referential integrity constraints, and business rules. What is an example of limits on data values? - Part numbers are seven-digit numbers start with the number 3. What is an example of a business rule for a manufacturing company? - Every purchased part will have a quotation from at least two suppliers. What happens during the Implementation Stage? - The database is constructed in the DBMS and populated with data; queries, forms, and reports are created; application programs are written; and all of it is tested. Also, users are trained, documentation is written, and the new system is put into use. What is the database development process a subset of? - The Systems Development Life-Cycle (SDLC) model. What are Use Cases? - Descriptions of the ways users will employ the features and functions of the new information system. What do Use Cases consist of? - A description of the roles uses will play when utilizing the new system, together with descriptions of activities' scenarios. In Use Cases, what is defined? - Inputs provided to the system and outputs generated by the system. What are Use Cases good for? - Providing sources of requirements and to validate the data model, design, and implementation. In addition to the Use Case requirements, what do you need to document? - Characteristics of data items. For each data item in a form, report or query, what needs to be determined? - Its data type, properties and limits on values. During the process of establishing requirements system, what do developers need to document? - Business rules that constrain actions on database activity. Ex.) Students must declare a major, no adviser may have more than 25 advisees, etc. When you write application programs, program logic must first be what? - Documented in flowcharts or object diagrams. When you create a database, data requirements must first be what? - Documented in a data model. What is the most popular way to create a data model? - The Extended Entity-Relationship Model (E-R Model) What are the most important elements of the E-R Model? - Entities, Attributes, Identifiers and Relationships. What is an Entity? - Something that users want to track. Ex.) CUSTOMER John Doe, PURCHASE 12345, PRODUCT A4200, etc. Entities of a given type are what? - Grouped into an Entity Class. Ex.) EMPLOYEE entity class is a collection of all EMPLOYEE entities What is an Entity Instance of an entity class? - The occurrence of a particular entity. Ex.) CUSTOMER 12345.