DM505, Spring 2006, 4th Quarter - Weekly Note 3

Lecture April 19

The lecture was spent partly as a kontaktgruppe meeting, partly discussing the handed out project.

Reading

Project text.

Lecture April 20

Relational model (slides: pdf). Transfer from E/R-model to relational model. Start on relational algebra (slides: pdf).

Reading

Ramakrishnan and Gehrke: Chapter 3 (you may skip 3.8). Sections 4.1-2 (not all of 4.2 covered yet).

Remarks

In Chapter 3, the book mixes SQL and the relational model - it is important to know that these are really different concepts (the latter is a data model, the former a database query and management language). Also, note that the ER-model and the relational model are different data models, despite the similarity between the words relationship and relation. The ER-model has no associated query language, and is only for data modeling. The relational model does have an associated query language, namely the relational algebra. The query language relational algebra is technically not the same as (the query part of) SQL, but the core query functionality of SQL is very much patterned over the relational algebra.

Lecture April 26 (Expected contents)

More on relational algebra. SQL.

Reading

Ramakrishnan and Gehrke: Section 4.2, Sections 5.1-6.

Exercises April 24

Exercises 2.6, 3.1, 3.4, 3.5, 3.6, 3.11, 3.12, 3.13, and 3.15 in Ramakrishnan and Gehrke.

Discussion of project, stage 1 (if needed).

Exercises April 27

Exercises 2.8, 3.18, 4.2, 4.3 (only the relational algebra versions of the queries) and 4.4 in Ramakrishnan and Gehrke.