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CS4433 Database Systems. Midterm Review. Midterm Exam. Time : Monday 03/08/2019 1:30pm --- 2:20pm Plan your time well Venue : in-class exam Closed book, closed note, but you can bring a one-page cheat sheet (A4, double side) Plan your strategy well
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CS4433Database Systems Midterm Review
Midterm Exam • Time: Monday 03/08/2019 1:30pm --- 2:20pm • Plan your time well • Venue: in-class exam • Closed book, closed note, but you can bring a one-page cheat sheet (A4, double side) • Plan your strategy well • No calculators or other electronic devices • Laptops, ipads, smart phones, etc. are prohibited • Any form of cheating on the examination will result in a zero grade, and will be reported to the university
Midterm Exam • What will be covered? • From “Introduction” to “Relational design” • Materials in both the slides and the textbook • How to do well in the midterm exam? • Review the materials carefully and make sure you understand them • Reexamine the homework and make sure you can work out the solutions independently • Discuss with your peer students • Discuss with the TA and me • Relax
DB: What and Why? • Besides file systems and OS, why bother yet another so-called DBMS? • Schemas & Data • DDL & DML
ER Model: Nothing but Drawing • Entities • Attributes • Relationships • One-one, one-many, many-many • Subclasses • Constraints • Keys, referential integrity, etc. • Weak Entity Set: Why & How?
Relational Model: A Step Further • Relation Schema • Primary key, Foreign key, Unique, NULL, Default • Translating ER to Relations • Entities • Relationships (many-many, many-one, one-one) • Weak entity set • Subclass
Relational Algebra: Let’s Do Math • Operators and operands • Set-based operators: intersection, subtraction, union… • Other basic operators: selection, projection,.. • Derived operators: division… • Cartesian product, theta-join, equi-join, natural join • Relational algebra expressions and expression trees • How to answer queries using relational algebra?
Relational Design: Design it right • Motivation • Functional dependencies & keys • Armstrong axioms • Closures • Normal forms and decomposition algorithms • BCNF • Lossless or lossy? • 3NF • Functional-dependency preserving or not? • Don’t overdo it