1. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–1 Database Systems Lecture/Workshop: Mon 1-3 LIB 1316; Wed 11 – 12, LH2 Lab: Thu 10-12, ACC, additional help: Mon or Tue? Judy Cushing - judyc@evergreen.edujudyc@evergreen.edu Office Hours: Thursdays 1-2pm, Lab I, 1003, 867-6652 Class web page: off the SOS web page, or academic.evergreen.edu/r/ricdan16/SOSdatabase/databaseHome.html Assignments due most Wednesdays Project Parts due Mondays or Thursdays Lab Aids: Dan Rice, Jeff Jones

2. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–2 Textbooks Required: Database Systems: The Complete Book, by Garcia-Molina, Ullman, and Widom (first edition), Prentice Hall, 2002. Recommended: (one of these) SQL in a Nutshell : A Desktop Quick Reference, Kevin E. Kline, Daniel Kline, O’Reilly. A Guide to the SQL Standard. C. J. Date and H. Darwen, Addison- Wesley, 1999. It is more succinct but perhaps a more useful summary, than the Melton-Simon book. SQL3 Complete, A Guide to the SQL Standard: A User's Guide to the Standard Database Language SQL, (fourth edition), by C.J. Date and Hugh Darwen, Addison-Wesley, 2000. SQL: 1999 - Understanding Relational Language Components, (first edition), by Melton and Simon, Morgan Kaufmann, 2002. If you are using PostgreSQL: Books on Unix, Perl, PHP, and CGI, PostgreSQL: Introduction and Concepts, Bruce Momjian, Addison- Wesley, 2001. This might also be on the web.

3. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–3 Evaluations I will evaluate you on your ability to design and implement a database application, and on your understanding of database concepts. I will consider: u Assignments and in class participation: about 30%. u Project: about 35%. u Exams: about 35%.

4. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–4 Project Build an application using a relational database system (SQL Server or PostgreSQL) accessed via Java and the web. The project has 8 parts (due Mondays or Thursdays), starting with design and ending with a complete application. The early programming assignments should be written in SQL, Java. Some students found it helpful to switch to JavaScript, HTML (PHP or Perl if Postgres) for the web-accessible part.

5. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–5 Project - tentative schedule 1.Project Part 1 due Jan. 14 (Mon) Choose a project and design an E/R diagram. 2.Project Part 2 due Jan. 24 (TH) Relational design. 3.Project Part 3 due Jan. 31 (TH) Create database in SQLServer. 4.Project Part 4 due Feb. 7 (TH) Queries, updates, and indexes. 5.Project Part 5 due Feb. 21 (TH) Embedded SQL. 6.Project Part 6 due Feb. 28 (TH) Views, constraints, and triggers. 7.Project Part 7 due Mar. 6 (Wed) Entire database application, in Java. 8.Project Part 8 due Mar. 11 (Mon) Database application, accessed via the web.

6. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–6 Typical Warning (for those taking this class elsewhere) The database class is a lot of work. But it is worth it. Of all courses you take, it may be the one that gets you a job…. We know that SOS gets people jobs, but database expertise does help…. Data is key to many applications….

7. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–7 Schedule Today: Jan. 7 u Intro, Entity-Relationship Model. u Read Chapter 1 and Sections 2.1, 2.3. Jan. 9 (W) u Weak Entity Sets, Entity-Relationship Design. u Read Sections 2.2, 2.4. Jan. 14 (M) u Relational Model, Functional Dependencies. u Read Sections 3.1-3.5. Project 1 due. Jan. 16 (W) u Normal Forms, Multivalued Dependencies. u Read Sections 3.6-3.7. Assignment 1 due. Date Topic Reading Week 1 Intro, E/R model Weak enitity sets, E/R design 1, 2.1, 2.3 2.2, 2.4 Week 2 Relational model, Functional Dependencies Normal forms, Multivalued dependencies 3.1-3.5 3.6-3.7

8. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–8 Syllabus The background and history of database management systems. The fundamentals of using a database management systems. Industry standards used for database management systems. Theoretical background of the relational model. Queries and Updates. Logic databases? Constraints and Triggers. Transactions and Security. Object-oriented, object-relational, semi-structured and XML database systems. Mediation and warehousing.

9. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–9 What is a Database Management System? 1. Manages very large amounts of data. 2. Supports efficient access to very large amounts of data. 3. Supports concurrent access to very large amounts of data. u Example: bank and its ATM machines. 4. Supports secure, atomic access to very large amounts of data. u Contrast two people editing the same UNIX file – last to write “wins” – with the problem if two people deduct money from the same account via ATM machines at the same time – new balance is wrong whichever writes last.

10. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–10 Relational Model Based on tables, as: acct #namebalance 12345Sally1000.21 34567Sue 285.48 …… … Today used in most DBMS's.

11. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–11 The DBMS Marketplace Relational DBMS companies – Oracle, Sybase – are among the largest software companies in the world. IBM offers its relational DB2 system. With IMS, a nonrelational system, IBM is by some accounts the largest DBMS vendor in the world. Microsoft offers SQL-Server, plus Microsoft Access for the cheap DBMS on the desktop, answered by “lite” systems from other competitors. Relational companies also challenged by “object-oriented DB” companies, and XML data stores. But countered with “object-relational” systems, which retain the relational core while allowing type extension as in OO systems.

12. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–12 Three Aspects to Studying DBMS's 1. Modeling and design of databases. u Allows exploration of issues before committing to an implementation. 2. Programming: queries and DB operations like update. u SQL = “intergalactic dataspeak.” 3.DBMS implementation. Consider DBMS system components, p. 11.

13. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–13 Query Languages Employee NameDept Department DeptManager SQL SELECT Manager FROM Employee, Department WHERE Employee.name = "Clark Kent” AND Employee.Dept = Department.Dept Query Language Data definition language (DDL) ~ like type defs in C or Pascal Data Manipulation Language (DML) Query (SELECT) UPDATE SET = WHERE

14. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–14 Host Languages C, C++, Fortran, Lisp, COBOL Application prog. Local Vars DBMS Calls to DB Host language is completely general (Turing complete) but gives you no support Query language—less general "non procedural" and optimizable (Memory) (Storage)

15. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–15 Relational model is good for: Large amounts of data —> simple operations Navigate among small number of relations Difficult Applications for relational model: VLSI Design (CAD in general) CASE Graphical Data CPU ALU ADDER Adder A FA ALU ADDER Bill of Materials or transitive closure

16. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–16 Where number of "relations" is large, relationships are complex Object Data Model Logic Data Model OBJECT DATA MODEL 1.Complex Objects – Nested Structure (pointers or references) 2.Encapsulation, set of Methods/Access functions 3.Object Identity 4.Inheritance – Defining new classes like old classes Object model: usually find objects via explicit navigation Also query language in some systems

17. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–17 LOGIC (Horn Clause) DATA MODEL Prolog, Datalog if A1 and A2 then B prolog B:- A1 and A2 Functions s(5) = 6 (successor) Predicates with Arguments sum(X,Y,Z) X + Y = Z sum(X,0,X) means X + 0 = X (always true for all X) sum(X,s(Y),s(Z)):-sum(X,Y,Z) means X+(Y+1) = (Z+1) if X + Y = Z More power than relational Can Compute Transitive Closure edge(X,Y) path(X,Y) :- edge(X,Y) path(X,Z) :- path(X,Y) & edge(Y,Z)

18. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–18 Hierarchical 60’s 70's 80's 90’s now Relational Choice for most new applications Object BasesKnowledge Bases Network Multi-tiered (web) ArchitecturesXML Data Transfers and Transformations

19. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–19 Students Entity/Relationship Model Diagrams to represent designs. Entity like object = “thing.” Entity set like class = set of “similar” entities/objects. Attribute = property of entities in an entity set, similar to fields of a struct. In diagrams, entity set  rectangle; attribute  oval. ID namephone height

20. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–20 Relationships Connect two or more entity sets. Represented by diamonds. StudentsCourses Taking

21. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–21 Relationship Set Think of the “value” of a relationship set as a table. One column for each of the connected entity sets. One row for each list of entities, one from each set, that are connected by the relationship. StudentsCourses SallyCS180 SallyCS111 JoeCS180 ……

22. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–22 Multiway Relationships Usually binary relationships (connecting two E.S.) suffice. However, there are some cases where three or more E.S. must be connected by one relationship. Example: relationship among students, courses, Lab Aids. Possibly, this E/R diagram is OK: StudentCourse Taking Assisting Lab Aid

23. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–23 Works in CS180, because each Lab Aid works for all students. Connection student- LabAid is only via the course. But what if students were divided into sections, each headed by a LabAid? u Then, a student in CS180 would be related to only one of the LabAids for CS180. Which one? Need a 3-way relationship to tell.

24. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–24 StudentCourseLabAid AnnCS180Jan SueCS180Pat BobCS180Jan ……… Student Course LabAid Enrolls

25. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–25 Beers-Bars-Drinkers Example Our running example for the course. nameaddrlicense namemanfnameaddr BeerDrinker Bar Serves Frequents Likes

26. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–26 Multiplicity of Relationships Representation of Many-One E/R: arrow pointing to “one.” u Rounded arrow = “exactly one.” Many-many Many-oneOne-one

27. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–27 Example: Drinkers Have Favorite Beers nameaddrlicense namemanfnameaddr BeerDrinker Bar Serves Frequents Likes Favorite

28. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–28 One-One Relationships Put arrows in both directions. Design Issue: Is the rounded arrow justified? Design Issue: Here, manufacturer is an E.S. In earlier diagrams it is an attribute. Which is right? ManufacturerBeer Best- seller

29. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–29 Attributes on Relationships Shorthand for 3-way relationship: BarBeer Sells price BarBeer Sells price Price

30. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–30 A true 3-way relationship. u Price depends jointly on beer and bar. Notice arrow convention for multiway relationships: “all other E.S. determine one of these.” u Not sufficiently general to express any possibility. u However, if price, say, depended only on the beer, then we could use two 2-way relationships: price-beer and beer-bar. u Or better: just make price an attribute of beer.

31. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–31 Converting Multiway to 2-Way Baroque in E/R, but necessary in certain “object-oriented” models. Create a new connecting E.S. to represent rows of a relationship set. u E.g., (Joe's Bar, Bud, $2.50) for the Sells relationship. Many-one relationships from the connecting E.S. to the others. BarBeer The- Bar Beer The- Beer The- Price BBP

32. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–32 Roles Sometimes an E.S. participates more than once in a relationship. Label edges with roles to distinguish. HusbandWife d 1 d 2 d 3 d 4… Drinker Married husbandwife

33. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–33 Notice Buddies is symmetric, Married not. u No way to say “symmetric” in E/R. Design Question Should we replace husband and wife by one relationship spouse? Buddy1Buddy2 d 1 d 2 d 1 d 3 d 2 d 1 d 2 d 4… Drinker Buddies 12

34. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–34 More Design Issues 1. Subclasses. 2. Keys. 3. Weak entity sets. (Next class.)

35. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–35 Subclasses Subclass = special case = fewer entities = more properties. Example: Ales are a kind of beer. In addition to the properties (= attributes and relationships) of beers, there is a “color” attribute for ales.

36. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–36 E/R Subclasses Assume subclasses form a tree (no multiple inheritance). isa triangles indicate the subclass relation. namemanf Beer Ale color isa

37. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–37 Different Subclass Viewpoints 1. E/R viewpoint: An entity has a component in each entity set to which it logically belongs. u Its properties are the union of the properties of these E.S. 2. Contrasts with object-oriented viewpoint: An object (entity) belongs to exactly one class. u It inherits properties of its superclasses. namemanf Beer Ale color isa Pete’s Ale

38. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–38 Multiple Inheritance Theoretically, an E.S. could be a subclass of several other entity sets. namemanf Beers namemanf Wines Grape Beers isa

39. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–39 Problems How should conflicts be resolved? Example: manf means vintner for wines, bottler for beers. What does manf mean for “grape beers”? Need ad-hoc notation to resolve meanings. In practice, we shall assume a tree of entity sets connected by isa, with all “isas” pointing from child to parent.

40. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–40 Keys A key is a set of attributes whose values can belong to at most one entity. In E/R model, every E.S. must have a key. u It could have more than one key, but one set of attributes is the “designated” key. In E/R diagrams, you should underline all attributes of the designated key.

41. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–41 Example Suppose name is key for Beers. Beer name is also key for ales. u In general, key at root is key for all. namemanf Beers Ales color isa

42. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–42 Example: A Multiattribute Key Possibly, the combination of hours + room also forms a key, but we have not designated it as such. deptroom Courses numberhours

43. Winter 2002 Judy Cushing, Art Keller, Jeff Ullman 1–43 In Class exercise (if time) or Assignment for Wednesday (for those who did SOS this Fall) Convert the UML for EU-Bid and EU-Lease to an ER diagram. Merge them into a design for one database.