The NTILE Function
The SQL NTILE() is a window function that allows you to break a table into a specified number of approximately equal groups, or <bucket count>. For each row in a grouping, the NTILE() function...
View ArticleWhen an update doesn’t update
Tell me if you’ve heard this one before: I changed data from my application, but when I checked the database, I couldn’t see the change! I’ve seen this. Loads. It can be quite perplexing for folks...
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Using a SQL Tokenizer
Imagine this: you have several directories full of SQL script files, and you need to know where a certain table is used. You’d rather like the context too, so you can check the whole SQL Expression and...
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Eager Aggregation in SQL queries
Aggregation is a widely used way to summarize the content of a database. It is usually expressed with GROUP BY clause or just using aggregate functions (like COUNT or SUM). When the database engine...
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Two-Dimensional Interval Packing Challenge
Packing intervals is a classic SQL task that involves packing groups of intersecting intervals to their respective continuous intervals. In mathematics, an interval is the subset of all values of a...
View ArticleDepartment of Redundancy Department
Ever wonder all the reasons that we use databases instead of file systems? While we don’t think of it too much anymore, the first reason that databases came into existence was to remove redundancies....
View ArticleSQL Logic
In this article, I will discuss the history and thinking behind several types of logic that are typically associated with writing relational database code. Because of how relational databases implement...
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Database Subsetting and Data Extraction
Let’s start by defining a subset and why you would require a data subset? When dealing with the development, testing and releasing of new versions of an existing production database, developers like to...
View ArticleThe CHECK() Constraint
One of the many ways a relational table differs from the file structures used by pre-relational storage systems is that the tables, rows and columns can have constraints on them. This allows you to...
View ArticleConcepts and Issues in Test Data Generation
Data generation is the science and art of providing data for database development work that is as realistic and controllable as possible. The skills of generating realistic data are an essential part...
View ArticleLIKE Constraints
In this article, I will cover a bit about the LIKE operator, including how it works, and a bit of history about why it is like it is. After establishing this, I will discuss a bit about how you can...
View ArticleBad 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...
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Database Sharding: Strategies for Seamless Scaling and Performance Optimization
Companies of all sizes and across industries are struggling to cope with an explosion of data never before seen in the short history of computing. As applications reach new levels of sophistication...
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 ArticleConsistency and Concurrency in NewSQL Database Systems
Companies today require database systems that are reliable and capable of efficiently handling large volumes of data and numerous transactions. Traditional relational databases, once the foundation of...
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...
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