Mon, Sep 27, 1999
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- Handout Codd's original paper in CACM

- Review of Basic Relational Operations

- NOT Sportscar example

- Cartesian Product: Actors and Actresses

- Would we have a situation when we multiply
  a relation with itself?
	Eg: if we want to have "teams" with
            with two students in it

- How do we ensure that the students are different?
  Ans: Theta-Join
	- A cartesian product followed by a select

- How do we ensure that the same combination of students is not listed twice?
  Ans: Use a unidirectional comparison (<, > etc.) instead of <>
  Assumption: Any type can be compared ordinally
              - integers, reals etc.
	      - strings: use lexicographic ordering

- Theta Join is a subset of Cartesian Product

- Theta Join and Cartesian Product have the same # columns
- Theta Join potentially has lesser # rows

- Quotient Operator
  Example: List of Graduating Students
  Exercise: Recast in terms of basic operators

Wed, Sep 29, 1999
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- Return to the Quotient

- Natural Join

- Connections between:
	- Cartesian Product
	- Theta Join
	- Natural Join

- Natural Join = Theta-Join,
                 on the condition that "like attributes are the same"
		 followed by a project that removes common columns


- PC Manufacturers Problem Handout 
	; write various queries in various forms

- Solved query problems 1 (three parts) and 2 (two parts)

Fri, Oct 1, 1999
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- Remaining query problems in handout