2. Introduction to Database Development zThe Database zThe Data Base Management System (DBMS) zCreating a Database zComponents of Applications zDeveloping Databases

3. The Database zComponents of database systems (Fig. 2-1) zThe database is processed by the DBMS. zThe DBMS is used by both developers and users, either directly or indirectly via application programs.

4. zUser’s Data (pg. 27,28) zMetadata: Description of the database structure ( Fig. 2-2) zOverhead data e.g. indexes, linked lists, etc. (Fig. 2-3) zApplication Metadata: Used to store the structure and format of user forms, reports, queries, and other application components. The database includes:

5. The DBMS zThe Design Tools Subsystem çA set of tools to facilitate the design and creation of the database and its applications. zRun-time Subsystem çProcesses the application components that are developed using the design tools.

6. zThe DBMS Engine çIs the intermediary between the design tools and run-time subsystems and the data itself. çTranslates the requests of the other two components into commands to the operating system to read or write data on physical media. çAlso handles transaction management, locking, and backup and recovery.

7. Creating the Database zDatabase schema defines a database’s structure, its tables, relationships, domains, and business rules. zTables (Fig. 2-4, 2-5) çCAPTAIN(CAPTAIN_ID, CaptainName, Phone, Street, City, State, Zip) çITEM(ITEM_ID, Quantity, Description, Date-Out, Date-In, CAPTAIN_ID) zRelationships e.g. One-to-many

8. Domains: Set of values for a column Business Rules i.e., restrictions on actions Primary and Foreign keys

9. Components of Applications zForms (Fig. 2-6, 2-7) çUser for easier and more user-friendly data entry. zQueries (Fig. 2-8, 2-9) çQuerying the data to answer questions or to identify problems or particular situations. çCan be expressed using the data access language (SQL- Standard Query Language), or by using query-by-example (QBE)

10. zReports (Fig. 2-10, 2-11) çFormatted displays (output) of database data. zMenus (Fig. 2-12) çUsed to organize application components (command menu) zApplication Programs (Fig. 2-13, 2-14)

11. Developing Databases zTop-down development çFrom the general to the specific. Strategic goals -> Information requirements -> Necessary systems -> Data model zBottom-up development çBegins with the need to develop a specific system. zData Modeling çA model of the user’s data which identifies what to store in the database, their structure, and relationships among them.