IT projects can hit problems that turn out to be due to an insufficient understanding of the basic data and data-types, rather than the database design. It is a sorely neglected topic that might seem to be trivial, but certainly isn't. The DBA, with a broad perspective on corporate data can do a great deal to help application developers to avoid the common mistakes that so often happen, and Joe Celko's Stairway gives the busy IT professional a crash course to understanding the nature of the data being processed.  Read more...

Joe discusses Hierarchical, Vector and Concatenation encoding before rounding up with general guidelines for designing encoding schemes.  Read more...

Joe discusses how to deal with the kinds of encoding schemes, how to use them and how to design them. He discusses Enumeration, Measurement, Abbreviation and Algorithmic categories   Read more...

Joe Celko introduces more powerful scales such as Interval, Log interval and ratio scales; before moving on to conversions, punctuation and units. Finally he gives guidelines as to how best to use scales in a database.  Read more...

Joe Celko discusses Nominal, Categorical, Absolute, Ordinal and Rank scales. These are the weakest scales we can use, starting with the weakest.  Read more...

Joe Celko tackles the most difficult of all the types of data handled by SQL, temporal data, and explains how to avoid the commonest traps for the unwary programmer  Read more...

Character-handling in SQL is not particularly straightforward, and confusion about collation and character encoding is a common cause of problems with searching, joining, and sorting.  Read more...

A confusion about the nature of numbers can lead to a number of problems in database applications. Joe Celko gives a simple guide to the subject  Read more...