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A DBMS EXAMPLE SECTION 2 A broad overview of a simple DBMS The Database • Main components Design Tools Database Database Contains User’s Data Metadata Indexes Application Metadata D B M S E n g i n e Table Creation Tool Developer Form Creation Tool Query Creation Tool Report Creation Tool Procedural Language Compiler Application Programs Run Time Users Form Processor Query Processor Report Writer Procedural Language Run Time Application Programs User Data • Today most databases represent user data as relations StedentName StudentPhone AdvisorName AdvisorPhone Baker, Rex 232-8897 Parks 236-0098 Charles, Mary 232-0099 Parks 236-0098 Johnson, Beth 232-4487 Jones 236-0110 Scot, Glen 232-4444 Parks 236-0098 Zylog, Frita 232-5588 Jones 236-0110 StedentName StudentPhone AdvisorName Baker, Rex 232-8897 Parks AdvisorName AdvisorPhone Charles, Mary 232-0099 Parks Parks 236-0098 Johnson, Beth 232-4487 Jones Jones 236-0110 Scot, Glen 232-4444 Parks Zylog, Frita 232-5588 Jones Metadata • A database is self-describing, which means that it contains a description of its structure as part of itself TableName Number of Columns Primary Key Student 4 StudentNumber Advisor 3 AdvisorName Course 3 CourseNumber Enrollment 3 {StudentNumber,CourseNumber} SysTables Table Column Name Table Name Data Type Length StudentNumber Student Integer 4 FirstName Student Text 20 LastName Student Text 30 Major Student Text 10 AdvisorName Advisor Text 25 Phone Advisor Text 12 Department Advisor Text 15 CourseNumber Course Integer 4 Title Course Text 10 NumberHours Course Decimal 4 StudentNumber Enrollment Integer 4 EnrollmentNumber Enrollment Integer 4 Grade Enrollment Text 2 SysColumns Table Indexes • Also called “overhead data” STUDENT DATA TABLE StudentNumber FirstName LastNamne Major 100 James Baker Accounting 200 Mary Abernathy Information Systems 300 Beth Jackson Accounting 400 Eldridge Johnson Marketing 500 Chris Tifte Accounting 600 John Smathers Information Systems 700 Michael Johnson Accounting LASTNAME INDEX LastName StudentNumber Abernathy 200 Baker 100 Major StudentNumber Jackson 300 Accounting 100, 300, 500, 700 Johnson 400, 700 Information Systems 200, 600 Smathers 600 Marketing 400 Tufte 500 MAJOR INDEX The DBMS • DBMS products vary greatly • First products in late 1960’s • Continually enhanced • Microsoft Access Design Tools Subsystem • Facilitates design and creation of the DB and its applications • Also provides programming languages Run-Time Subsystem • Processes the applications • Also provides application program interface The DBMS Engine • Intermediary between the design tools , the run-time subsystems, and the data • Also involved with transaction management Creating the Database • Database schema • The foundation A Schema Example • An example of a University sports facility • Tables: – CAPTAIN (Captain_Id, CaptainName, Phone, Street, City, State, Zip) – ITEM (Item_Id, Quantity, Description, DateOut, DateIn • Relationships: – CAPTAIN (Captain_Id, CaptainName, Phone, Street, City, State, Zip) – ITEM (Item_Id, Quantity, Description, DateOut, DateIn, Captain_Id) Schema: domains • A set of values that a column (attribute) may have – Length – Type of field Schema: rules • Restrictions on activities that need to be reflected in the data base and its applications – To checkout equipment a captain must have – No captain may have more than Creating Tables • Once the schema is defined • Use the database creation tool Defining Relationships • Relationship between CAPTAIN and ITEM? • Foreign key • Key advantage of a relationship Components of Applications • Consists of : – Forms – Queries – Reports – Menus – Application Programs Forms • Forms allow data entry – data sheet view – data entry form Data Sheet Entry Captain Registration Form Data Entry Form – with form-in-form feature Creating a Form Queries • Query data to identify problems or answer questions • SQL • Query by example Query By Example Result of the Query Reports • A formatted display of database data • Banded report writer Application Programs • Can be written in a language specific to the DBMS or a standard language that interfaces with the DBMS Visual Basic Code to Enforce a Rule