Bad Data and Dirty Databases
Many years ago, my wife and I wrote an article for Datamation, a major trade publication at the time, under the title, “Don’t Warehouse Dirty Data!” It’s been referenced quite a few times over the...
View ArticleUniqueness, Keys, and Identity
If you’ve ever had a traditional logic course, you’ll have run into “The Law of Identity” as the founding principle of all Western thought. It says that: “To be is to be something in particular; to be...
View ArticleRounding Numbers
I would hope by now everybody has figured out when you see a price like $39.99 that it might as well be forty bucks. Dropping that penny from the price is done is to fool the consumer! Since we read...
View ArticleTransactions
By now, pretty much everyone has heard the stories about the first computers. They were huge, cost a fortune, required incredible amounts of air conditioning, and perhaps more importantly, ran batch...
View ArticleData Control Language (aka Security)
Like ancient Gaul, SQL is divided into three sub- languages. The DDL (Data Declaration Language) declares the data. This is where we find the data types, constraints, references and other structures...
View ArticleVIEW Objects
A view is a virtual table, created when it’s invoked by the < view name>. The goal we had in the standards is to make it behave as much like a base table as possible. Creating a View The syntax...
View ArticleTemporary Tables
There is a feature of SQL I have not seen used much and probably with good reason. It’s the use of temporary tables. These are declared with the expected DDL. Since they were relatively easy to add to...
View ArticleScales & Measurements
If you’re going to work with databases, you probably ought to know something about data. In particular, we don’t put data directly into a database; we have to encode it and represent it in a format...
View ArticleThe CREATE DOMAIN Statement
One of the least known, least used features of SQL is the CREATE DOMAIN statement. It does not exist in SQL Server as of SQL Server 2022, but it has been a part of PostgreSQL since 7.3. Some...
View ArticleData Elements on a Nominal Scale
“On a scale from 1 to 10, what color is your favorite letter of the alphabet?” –Slogan on a T-shirt This is one of my favorite T-shirt gags because it teaches something about data types, scales and...
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