C.J. Date

Nullology: The Zen of Database

Date: This event took place live on May 07 2010

Presented by: C.J. Date

Duration: Approximately 75 minutes.

Cost: Free

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Nullology is the study of the empty set. Of course, sets crop up all over the place in the database world; but the question is--and it's a crucial one--what happens if the set under consideration happens to be empty? For example, a relation contains a set of tuples: what about the possibility of a relation containing no tuples at all? Now this particular possibility is a familiar one, because a relation with no tuples is much like a conventional empty file. Even in this case, however, there are interesting aspects to consider that are probably unfamiliar to most database professionals. And there are many other places in the database world where the empty set rears its head, several of them unfamiliar and yet of fundamental importance. Such matters are the subject of this presentation.

This 75-minute webcast will cover:

  • Relations with no tuples
  • Relations with no attributes
  • Empty lists of operands
  • Empty partitions of heading
  • Empty determinants and empty keys
  • Empty types
  • Note: the presentation overall can be seen as an elaboration of the material touched on, but not discussed in depth, in Chris Date's recent O'Reilly master class "SQL and Relational Theory: How to Write Accurate SQL Code."

    Prerequisites: Attendees will be expected to have a basic understanding of the relational model.

    About C.J. Date

    C.J. Date has a stature that is unique within the database industry. C.J. is a prolific writer, and is well-known for his best-selling textbook: An Introduction to Database Systems (Addison Wesley). C.J. is an exceptionally clear-thinking writer who can lay out principles and theory in a way easily understood by his audience.