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Databases Terms & Concepts • • • • • Field Record File / Table Database Entity • • • • • Attribute Key Field / Primary Key Candidate Key Composite Key Foreign Key Traditional File Processing Flat File Example – (Hospital) Radiology Department Patno Fname Lname Street City 1111 Jane Smith Main Service Cape X-ray Servchrg $125.00 Pathology Department Patno Fname Lname Street City 1111 Jane Smith Main Service Cape Blood Servchrg $15.00 Traditional File Environment Problems • • • • • • Data redundancy Data inconsistency Program-data dependence Lack of flexibility Poor security Lack of data sharing and availability Advantages of the Database Approach 1. Program-data independence 2. Minimal data redundancy 3. Improved data consistency 4. Improved data sharing 5. Increased productivity of application development 4-6 Advantages of the Database Approach (cont’d) 6. Enforcement of standards 7. Improved data quality 8. Improved data accessibility 9. Reduced program maintenance 4-7 Database Exercise • Create the following five tables using the fields listed below. Underline the Key field(s) for each table. Tables: Students Courses Zip_codes Student_addresses Instructors Fields: StudentID (2), Instructor_ID, City, Student_firstname, Zipcode (2), State, CourseID, Course_num, Instructor_firstname, Course_section, Address_ type, Student_lastname, Street, DOB, Entry_date, Instructor_lastname, Instructor_phone, Course_description, course_hours Database Exercise Students StudentID, St_FirstName, St_LastName, DOB, Entry_Date Courses CourseID, CourseNum, CourseSection, CourseDescription, CourseHours Zip_codes ZipCode, City, State Student_addresses StudentID, Street, ZipCode, AddressType Instructors InstructorID, Instructor_FirstName, Instructor_LastName, Instructor_Phone Flat File Example – Student Db StuID Fname Lname Street City 1111 Jane Smith Main 1111 Jane Smith 1111 Jane Smith State ZipCd Cape MO Sem 63701 Spring North Anna IL 62980 Spring Railrd Sike 63755 Spring MO Continued Year 2009 2009 2009 CID 0413 0413 0413 Course MI375 MI375 MI375 Sec 01 01 01 Desc MIS MIS MIS Hrs 3 3 3 Prof Schw Schw Schw Phone 7387 7387 7387 DrID DS1 JR3 Relational File Example Student Database SID Fname Lname 1111 Jane Smith Students SID Street Zip 1111 Main SID 1111 CID 2345 EID DS1 1111 3687 JR3 Phone Addtype 63701 2100 home CID CrsNum Sec Desc 0375 0301 MI375 MK304 MIS 3 MKTG 3 03 01 Fname Lname Dana Schwie James Ricks Hrs Course Schedule Student_Address Creating a Database • Designing – Data need to be organized for retrieval and analysis • Key elements of a database – Data » Normalization • Repeating groups – Structure » Data model • A map or a diagram representing entities and their relationships » Entity-Relationship (ER) Diagram • Distributing – Client / server networks • Partitioned database • Duplicate database Effective Management of Databases • Database Administrator (DBA) – Responsible for development and management of databases • • • • Works with system analysts and programmers Works with users and managers Implements security features Grants access rights – One of the key actors in creating a successful database 4-13 Entering Data • Forms – Enter data about a record – Field in a form corresponds to attribute in a record – Used to add, modify, or delete data 4-14 Querying Data • Query: Used to retrieve information • Structured Query Language (SQL) – Example: Display students who earned an “A” – Writing SQL queries can become very complex 4-15 Query by Example • Simpler than SQL • Drag-and- drop features • Construct a sample of the data we would like to see 4-16 Creating Database Reports • Report – Compilation of data from the database • Report generators – Retrieve, manipulate, and display data • Example o Quarterly sales for a restaurant • Adding • Grouping 4-17 Operational vs. Informational Systems 4-18 Data Warehouses and Data Marts • Data Warehouse – Integration of multiple large databases and other information sources into a single repository – Pull together, integrate, and share critical corporate data throughout the firm • Data Mart – Data warehouse that is limited in scope – Customized for the decision support applications of a particular end-user group 4-19 Associations TB-20 • Used to relate information between tables • Needed to retrieve information • Example: Basketball league database
