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 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