RELATIONAL DATABASE MODEL Database – logical collection of information you organize and access according to the logical structure of the information Relational database – uses a series of two-dimensional tables or files to store information in the form of a database McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases Are… Collections of information Created with logical structures With logical ties within the information With built-in integrity constraints McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Collections of Information Databases have many tables Solomon Enterprises as a concrete provider. Tables include: Order Customer Concrete Type Employee Truck McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Collections of Information McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Created with Logical Structures In databases, row numbers are irrelevant In databases, columns have logical names such as Order Date and Customer Name Data dictionary – contains the logical structure of the information in a database McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Logical Ties within the Information Logical ties must exist between the tables Logical ties are created with primary and foreign keys Primary key – field (or group of fields in some cases) that uniquely describe each record McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Logical Ties within the Information Foreign key – primary key of one file that appears in another file Foreign keys help create relationships among tables Table = file = relation (don’t confuse yourself) McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Logical Ties within the Information McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Databases – Built-in Integrity Constraints Integrity constraint – rule that helps ensure the quality of information Examples Primary keys must be unique Foreign keys cannot be blank Sales price cannot be negative Phone numbers must have an area code McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

DBMS TOOLS Database management system (DBMS) – helps you specify the logical organization for a database and access and use the information within a database Word processing software = document Spreadsheet software = workbook DBMS software = database McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

DBMS TOOLS 5 software components DBMS engine Data definition subsystem Data manipulation subsystem Application generation subsystem Data administration subsystem McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

DBMS TOOLS McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

DBMS Engine DBMS engine – accepts logical requests, converts them into their physical equivalent, and accesses the database and data dictionary DBMS engine separates the logical from the physical McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

DBMS Engine Physical view – how information is arranged, stored, and accessed on a storage device Logical view – how you (knowledge worker) need to arrange and access information Databases – you work only with logical views McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Definition Subsystem Data definition subsystem – helps you create and maintain the data dictionary and define the structure of the files in a database Must create data dictionary for a database before entering any information Extended Learning Module J covers this McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Manipulation Subsystem Data manipulation subsystem – helps you add, change, and delete information Primary interface between you and a database Views Report generators QBE tools SQL McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Views View – allows you to see the contents of a database file Similar to a spreadsheet view Make changes Sort Query McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Views Sort Find Add a new record McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Report Generators Report generator – helps you quickly define formats of reports and what information you want to see in a report Save report formats to use later Uses a wizard interface McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Report Generators Specify the fields you want in a report Specify the layout of the report McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Report Generators McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

QBE Tools Query-by-example (QBE) tool – helps you graphically design the answer to a question “What driver most often delivers concrete to Triple A Homes?” McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

QBE Tools McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

SQL Structured query language (SQL) – standardized fourth-generation language found in most DBMSs Performs same task as QBE Uses sentence structure instead Mostly used by IT people McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Application Generation Subsystem Application generation subsystem – contains facilities to help you develop transaction-intensive applications Data entry screens (called forms in Access) Programming languages Mostly used by IT people McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Administration Subsystem Data administration subsystem – helps you manage the overall database environment Backup and recovery Security management Query optimization Concurrency control Change management McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Administration Subsystem Backup and recovery Periodically back up information Recover a database after a failure Security management Who has access to what information Who can perform CRUD tasks on information McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Administration Subsystem Query optimization Restructure physical view to optimize response times to queries Concurrency control What happens if two people simultaneously try to change the same information? McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.

Data Administration Subsystem Change management What is the effect of structural changes to a database? What if you add a new column? What happens if you delete a column? What happens if you change a column’s attributes? McGraw-Hill © 2007 The McGraw-Hill Companies, Inc. All rights reserved.