5-1 McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.

5-2 Fundamental Data Concepts Character: single alphabetic, numeric or other symbol Field or data item: a grouping of related characters Represents an attribute (a characteristic or quality) of some entity (object, person, place or event) Example: salary Record: grouping of all the fields used to describe the attributes of an entity Example: payroll record with name, SSN and rate of pay

5-3 Fundamental Data Concepts File or table: a group of related records Database: an integrated collection of logically related data elements

5-4 Data Planning Process Enterprise Model Defines basic business process of the enterprise Defined by DBAs and designers with end users Data Modeling Relationships between data elements Entity Relationship Diagram (ERD) common tool for modeling

5-5 Entity Relationship Diagram

5-6 ERD Symbols Entity Relationship Attribute

5-7 James Bond Database Agents Appear in Films Agent Number Name Film Number Film Agent Number

5-8 SQL SELECT is used to retrieve zero or more rows from one or more tables in a database FROM is used to indicate from which tables the data is to be taken, as well as how the tables JOIN to each other.

5-9 SQL WHERE is used to identify which rows to be retrieved GROUP BY is used to combine rows with related values into elements of a smaller set of rows. ORDER BY is used to identify which columns are used to sort the resulting data.

Texas Tech enrolls students in courses that are taught by professors. Tech tracks students by first name, last name, eRaider username, and SSN. Courses have a course ID, a department, a course number, and a section number. Professors have a first name, last name, eRaider username, rank, and SSN. 5-10

5-11 McGraw-Hill/Irwin Copyright © 2007 by The McGraw-Hill Companies, Inc. All rights reserved.