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
8,469 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
2,413 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)
18,742 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
3,335 reads
Learn a little basic graph theory in this article that replaces a GROUP BY clause.
2022-07-04 (first published: 2019-10-17)
11,980 reads
This article presents a way that finds a perfect match in any bipartite graph or shows why one cannot exist.
2021-09-06
2,932 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
8,073 reads
This article shows how to solve a gaps and islands problem using simple algebra.
2020-03-10
5,005 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
7,174 reads
An interesting tutorial for linking SQL Server to a Blackberry device and viewing images.
2011-02-09
11,422 reads
By Brian Kelley
There's a great article from MIT Technology Review about resetting on the hype of...
By Steve Jones
etherness – n. the wistful feeling of looking around a gathering of loved ones,...
By Steve Jones
A customer was asking about tracking logins and logouts in Redgate Monitor. We don’t...
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What does this code return in SQL Server 2025+? (assume the database has an appropriate collation)
SELECT UNISTR('Hello 4E16754C') AS 'A Classic';
A: 
B: 
See possible answers