1. DATABASES Define Software that can hold large amounts of data and allow users to retrieve specific information quickly. (Access, Oracle, etc.) Data is stored in a highly organized fashion and methods used to store it can be complex. Types Flat file Only one table Used for very small databases Relational Multiple tables with common elements (relational) Examples Customer information held by almost all businesses Student information held by Universities Search Engines (Yahoo, Lycos, MSN, etc.) Government databases (SS, FBI, etc.)

2. DATABASE COMPONENTS Tables Related information organized in rows and columns. Structure is well-defined with very specific rules that must be followed if problems are to be avoided later (fields, relationships, constraints) Fields: Column identifiers Record: One row of information in the table All records in a table are the same length (in Bytes) regardless of the information contained in them. Data: Numerical and text are two most common data-types. There are usually many others (Date, Currency, etc.) Student IDLast NameFirst NameAddressPhone 123-44-5678SmithJohn11 Anywhere111-2222 111-22-3333JonesJane22 Hereitis222-3333 444-55-6666JohnsonFredBox 12333-4444 Fields: Student ID, Last name, First Name, Address, and Phone Records: There are 3 records in this table. STUDENT_INFO

3. DATABASE COMPONENTS Student IDLast NameFirst NameAddressPhone 123-44-5678SmithJohn11 Anywhere111-2222 111-22-3333JonesJane22 Hereitis222-3333 444-55-6666JohnsonFredBox 12333-4444 Additional Table Components Unique Field: Primary Key Field. (May be more than one field.) All other fields should be dependent on the the primary key field Index: Managed by the database software. Allows for fast access to the record of interest. STUDENT_INFO

4. RELATIONAL DATABASE Student IDLast NameFirst NameAddressPhone 123-44-5678SmithJohn11 Anywhere111-2222 111-22-3333JonesJane22 Hereitis222-3333 444-55-6666JohnsonFredBox 12333-4444 Multiple tables related through common fields (foreign keys) Used to link tables together to make queries more efficient Student IDSemesterGPA 111-22-3333F19992.9 111-22-3333S20003.2 444-55-6666F19993.1 444-55-6666S20003.7 STUDENT_INFO STUDENT_GPA

5. DATABASE COMPONENTS Student IDLast NameFirst NameAddressPhone 123-44-5678SmithJohn11 Anywhere111-2222 111-22-3333JonesJane22 Hereitis222-3333 444-55-6666JohnsonFredBox 12333-4444 Queries Questions asked of the database. Allow the user to extract information from the data. Answering a query results in another table built from existing tables. Example “What is the name (first and last) and phone number of students with the last name Smith?”…Query Result 1 What is Fred Johnson’s cumulative GPA?...Query Result 2 Strict rules for querying a database. (SQL) STUDENT_INFO Last NameFirst NamePhone SmithJohn111-2222 Query Result 1 GPA 3.4 Query Result 2 Student IDSemesterGPA 111-22-3333F19992.9 111-22-3333S20003.2 444-55-6666F19993.1 444-55-6666S20003.7 STUDENT_GPA

6. DATABASE COMPONENTS Reports Formal document created to present specific information from a database. Document created from one or more queries and usually contains considerable Formatting. Forms Interface created for users of the database to view and usually add information to the database.