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
7,256 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
2,329 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)
18,273 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
3,208 reads
Learn a little basic graph theory in this article that replaces a GROUP BY clause.
2022-07-04 (first published: 2019-10-17)
11,757 reads
This article presents a way that finds a perfect match in any bipartite graph or shows why one cannot exist.
2021-09-06
2,809 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
7,412 reads
This article shows how to solve a gaps and islands problem using simple algebra.
2020-03-10
4,926 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
7,055 reads
An interesting tutorial for linking SQL Server to a Blackberry device and viewing images.
2011-02-09
11,411 reads
By Steve Jones
Recently I’ve been looking at archiving some data at SQL Saturday, possibly querying it,...
By Brian Kelley
Just as it's important to take care of our physical health (and I'm guilty...
By Zikato
In SQL Server, using the KILL command to terminate a session results in an...
My agency has been using the combo of on-premises SQL Server for the back...
Development Environment I am learning how to use pyodbc and accessing database in SQL...
We are seeing multiple frequent deadlocks occurring with the following extract of code, which...
I want to enable two trace flags, 4199 and 4137, for a single query. How should I do this:
-- A
SELECT
a.AddressID
, a.AddressLine1
, a.AddressLine2
, a.City
, a.StateProvinceID
, a.PostalCode
, p.FirstName
, p.LastName
FROM
Person.Address a
INNER JOIN person.Person AS p
ON p.rowguid = a.rowguid
WHERE
City = 'SEATTLE'
AND PostalCode = 98104
OPTION (QUERYTRACEON 4199, 4137);
-- B
SELECT
a.AddressID
, a.AddressLine1
, a.AddressLine2
, a.City
, a.StateProvinceID
, a.PostalCode
, p.FirstName
, p.LastName
FROM
Person.Address a
INNER JOIN person.Person AS p
ON p.rowguid = a.rowguid
WHERE
City = 'SEATTLE'
AND PostalCode = 98104
OPTION (QUERYTRACEON 4199, QUERYTRACEON 4137);
-- C
SELECT
a.AddressID
, a.AddressLine1
, a.AddressLine2
, a.City
, a.StateProvinceID
, a.PostalCode
, p.FirstName
, p.LastName
FROM
Person.Address a
INNER JOIN person.Person AS p
ON p.rowguid = a.rowguid
WHERE
City = 'SEATTLE'
AND PostalCode = 98104
OPTION (QUERYTRACEON 4199), (QUERYTRACEON 4137);
See possible answers