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
8,433 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
2,411 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)
18,738 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
3,334 reads
Learn a little basic graph theory in this article that replaces a GROUP BY clause.
2022-07-04 (first published: 2019-10-17)
11,976 reads
This article presents a way that finds a perfect match in any bipartite graph or shows why one cannot exist.
2021-09-06
2,931 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
8,055 reads
This article shows how to solve a gaps and islands problem using simple algebra.
2020-03-10
5,004 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
7,169 reads
An interesting tutorial for linking SQL Server to a Blackberry device and viewing images.
2011-02-09
11,420 reads
By Brian Kelley
If you're looking for particular "Black Friday" deals, here is what I've seen advertised...
By SQLPals
Dry-run xp_delete_file Before Actually Deleting Files? xp_delete_file doesn’t really have a...
By Brian Kelley
In the United States, today is Thanksgiving. The intent behind the holiday is to...
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In SQL Server 2025, what does this code return?
SELECT '1' || '0'See possible answers