Introduction This article celebrates a classic algorithm [1] of Dijkstra (1930 – 2002) which finds a path of minimal cost between any pair of nodes in an undirected graph. His procedure is widely recognized as a fundamental tool for examining communication and transportation networks (eg. Google Maps) and is surprisingly simple. By his own admission, […]
2024-01-05
8,700 reads
Introduction The sp_HorizontalTree procedure introduced here may be used to audit tables with dependent columns. A column is dependent on another if the meaning of the first column depends on the meaning of the second. For example, in a table containing accounting information, the meaning of a Fiscal Quarter column depends on the Fiscal Year to […]
2023-06-16
2,425 reads
Introduction This article shows how to script a basic merge between two tables, without using MERGE. This can be handy when you're merging a pair of tables with hundreds of columns, since the script doesn't know anything about them. This technique introduces and populates some auditing columns (IS_DELETED, IS_INSERTED, IS_UPDATED, TRANSACTION_DATE) for each record, and runs fast. […]
2023-02-20 (first published: 2020-04-14)
18,790 reads
In this article, Glen Cooper provides code that allows you to process a tree, or undirected graph of data. Lots of hierarchies fall into this category and the ability to process them is valuable in many reporting situations.
2023-01-20
3,381 reads
Learn a little basic graph theory in this article that replaces a GROUP BY clause.
2022-07-04 (first published: 2019-10-17)
12,009 reads
This article presents a way that finds a perfect match in any bipartite graph or shows why one cannot exist.
2021-09-06
2,964 reads
Introduction This article shows how common table expressions (CTE) in SQL Server are naturally suited for navigating trees, such as finding its longest path, or diameter. Recall that a tree is an undirected graph where unique paths exist between any two nodes (i.e. vertices). Any node may be selected as its top node, with its […]
2021-04-19
8,166 reads
This article shows how to solve a gaps and islands problem using simple algebra.
2020-03-10
5,025 reads
In this article, we see how SQL can be used to determine matches between two groups, given a set of preferences.
2020-01-23
7,188 reads
An interesting tutorial for linking SQL Server to a Blackberry device and viewing images.
2011-02-09
11,434 reads
Every PostgreSQL migration eventually hits the same fork in the road. The database is...
By Steve Jones
I’m off on vacation today. Which is a little weird as I just got...
By Arun Sirpal
Every DBA has a box like this. Sitting untouched for months. Nobody’s proud of...
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Comments posted to this topic are about the item Independence Day 2026
In the original Independence Day movie (1996), what type of computer did Jeff Goldblum use to connect to the alien mainframe? Take a guess, don't look it up or ask AI.
See possible answers