Tom Johnston
Tom Johnston is an independent consultant specializing in enterprise data architecture, and in relational, object-oriented and data warehouse modeling in various industries, including telecommunications, health care, banking, retailing and transportation. He can be reached at tjohnston@acm.org, and his Web site is www.MindfulData.org.
Recent Stories From this Author
Time and Time Again: Scenario 1, Transaction 2
November 19, 2008 In this column, we begin our discussion of bi-temporal updates
Time and Time Again: Scenario 1
November 5, 2008 With this column, the authors begin an example-driven presentation of asserted versioning.
Time and Time Again: The Logical Data Model for Asserted Versioning Examples
October 15, 2008 In this column, we present the logical data model of the five tables we will use to illustrate asserted versioning.
Time and Time Again: The Origins of Asserted Versioning
October 1, 2008 In this column, we present the schema of asserted versioning tables. Using a one-row policy table, we explain how to read the...
Time and Time Again: The Origins of Asserted Versioning
September 16, 2008 In this column, we discuss the origins of asserted versioning, an approach to temporal data management that has roots in both...
Time and Time Again: Versions and Episodes
September 3, 2008 This column introduces episodes, a core concept in asserted versioning. It explains the correspondences between episodes and...
Time and Time Again: Concluding Our Extended Taxonomy Discussion
August 13, 2008 This wraps up our classification of ways to manage time in databases. Each has its place in enterprise data architecture. Our...
Time and Time Again: The Importance of Bi-Temporal Data Management
July 30, 2008 To emphasize the relevance of our discussions to real-world data management issues, we will consider four hypothetical...
Time and Time Again: Managing Time in Relational Databases - A Revised Roadmap
July 16, 2008 I will present a side-by-side series of inserts, updates and deletes against non-temporal tables and against corresponding...
Time and Time Again
July 2, 2008 We are pleased to welcome Tom as our newest online columnist. This column is a continuation of his previous articles and will...
