IFS310: Module 10 Database Design - Physical design of files and databases

IFS310: Module 10 Overview of Database Design Capture Users’ “Views” of data –Forms, Screens, Reports Data Modeling (entity-based ERD) –Add keys, attributes, relationships (key-based, and fully-described ERD) Consolidate data models – One big ERD Determine Database Schema

IFS310: Module 10 Conventional Files Versus the Database Files are collections of similar records. Databases are collections of interrelated files. –Discuss advantages and disadvantages of each –Compare and Contrast

IFS310: Module 10 Databases A database management system (DBMS) is specialized computer software available from computer vendors that is used to create, access, control, and manage the database.

IFS310: Module 10

A Simple Logical Data Model

IFS310: Module 10

The Database Schema –Data type. Each DBMS supports different data types, and terms for those data types. –Size of the Field. Different DBMSs express precision of real numbers differently. –Required or NOT Required. Must the field have a value before the record can be committed to storage? –Domains. Many DBMSs can automatically edit data to ensure that fields contain legal data. –Default. Many DBMSs allow a default value to be automatically set in the event that a user or programmer submits a record without a value. –Referential Integrity. An integrity constraint specifying that the value (or existence) of an attribute in one relation depends on the value (or existence) of the same attribute in another relation

IFS310: Module 10 Other Considerations Denormalization Choices of storage formats File organizations Backup/Recovery Security of Data

IFS310: Module 10 Milestone 6: Database Design Design files / databases Fully attributed ER Diagram Data dictionary (all the data elements and data schema specified)