Fluency with Information Technology INFO100 and CSE100 Katherine Deibel Katherine Deibel, Fluency in Information Technology1 A database is made of Physical database: Tables actually stored on the hard disk Logical databases: On-the-fly virtual tables created by queries Queries: [programs written in SQL that] define how to make a logical table from physical tables How do we make each part? Katherine Deibel, Fluency in Information Technology2 Describe the data physically What are major clusters/higher-level notions of the data? How do they interact/relate with each other? Identify the logical structure Describe a role with the data Identify what fields are needed Write queries for just those fields Katherine Deibel, Fluency in Information Technology3 There is a technology more powerful than computers when it comes to designing software, databases, etc.? What is it? Pencil and paper Whiteboards and markers Blackboards and chalk Katherine Deibel, Fluency in Information Technology4 Why not start directly with the database software? Application locks you in to working in a certain order Paper-pencil gives you some flexibility Application will force you to attend to the details and not the general goals Katherine Deibel, Fluency in Information Technology5 Sketch relational structure using Entity-Relationship (ER) Diagrams Tables in boxes Lines show relationship and type of relationship Example: Specifying a 1-to-many relationship Faculty Student Katherine Deibel, Fluency in Information Technology6 Outline key fields and refine the relationships with the fields Katherine Deibel, Fluency in Information Technology7 Faculty_ID FirstName LastName Department DateHired Faculty Student_ID FirstName LastName MajorID Advisor Student 1 Build physical DB to avoid redundancy Each physical table represents one entity Expect that no physical table gives any user their exact view To build view, build a query that Joins tables together into a super table Trims out the items the user wants or needs Katherine Deibel, Fluency in Information Technology8 Database schemes (schema) Metadata specification that describes the database design Katherine Deibel, Fluency in Information Technology9 Katherine Deibel, Fluency in Information Technology10 A relationship is a correspondence between rows of one table and the rows of another table key Student_ID is used in each table, Find address for each student (Lives_At) Find the student for each address (Home_Of) Katherine Deibel, Fluency in Information Technology11 Katherine Deibel, Fluency in Information Technology12 The Initial Steps Katherine Deibel, Fluency in Information Technology13 You have been contacted by a high school to build a database for the athletics program What do you do? Katherine Deibel, Fluency in Information Technology14 CLIENTS Staff Coach Players(?) DATABASE DESIGNER Interviews the experts/clients Builds a list of design goals and rules for the database Katherine Deibel, Fluency in Information Technology15 Individuals are selected for a team Keep track of the points awarded to each student for participating for the awarding of school letters The Database has to keep track of student Athletes over five years with any given Athlete participating in multiple sports in a given year Katherine Deibel, Fluency in Information Technology16 Each high school student can play for 1 to 4 years. A player can play in 0, 1, or many sports each year Each team has many players Katherine Deibel, Fluency in Information Technology17 The high school has many teams. The high school is in one division. Each team has a gender. Each team is in a division. Each team has a coach. Each team has many players. Each student earns points for winning an event. Each student earns a letter by earning x points in a sport in a season. Each student may participate in zero, one, or many sports each year. Each student may play in sports for 1-4 years. Each student may play in zero, one, or many competitions at an event. Each coach can coach one or many teams Katherine Deibel, Fluency in Information Technology18 Major data entities Teams Athletes Katherine Deibel, Fluency in Information Technology19 The HS has many teams The HS is in one division Each team has a gender Each team is in a division Each team has a coach A team has many players Each student earns points for winning an event team_name n/a team_gender n/a coach_name one-to-many student_points team_wins event_name event_outcome Katherine Deibel, Fluency in Information Technology20 Major data entities Teams Athletes Events Katherine Deibel, Fluency in Information Technology21 student_id student_result_at_event student_points_to_date student_points_at_event student_first_name letters_sport_code student_middle_name letters_awarded_date student_last_name team_gender student_date_of_birth event_location team_name student_gender team_description student_address coach_name student_other_details team_other_details division_description sport_description event_name event_start_date event_end_date event_other_details Katherine Deibel, Fluency in Information Technology22 You keep adding More fields More relationships Perhaps you discover the need more entities (tables) Once complete, you implement the tables And then the logical begins Katherine Deibel, Fluency in Information Technology23 Designing a database is more about thinking than typing Sketch out the relationships on paper Identify the needs of the clients Key aspect is to separate the logical and physical aspects Physical is about entities and their relationships Logical is about the user Katherine Deibel, Fluency in Information Technology24 Work on GoPosts Make sure you understand Lab 9 Project 3 is about databases and spreadsheets Install Access on your home computer if you want Get ready for an interstellar vacation (I'm 100% serious) Katherine Deibel, Fluency in Information Technology25