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T-SQL bugs, pitfalls and best practices – subqueries

Itzik Ben-Gan resumes his blog series on T-SQL bugs, pitfalls, and best practices, treating an issue with correlated column references in subqueries.
The post T-SQL bugs, pitfalls and best practices...

Temporary Staging Tables

Watch this week’s episode on YouTube. SQL Server Spool operators are a mixed bag. On one hand, they can negatively impact performance when writing data to disk in tempdb....
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T-SQL Tuesday #114 – Puzzle Party

A few years back I started running regular SQL workshops in my workplace. Teaching beginners the basics of querying databases with SQL, as well as more advanced topics for...
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Splitting Strings With OPENJSON

Starting with SQL Server 2016, Microsoft provided a STRING_SPLIT function. It is a table-valued function that splits a string into rows of substrings, based on a specified separator character....

The Silent Bug I Find in Most Triggers

I don’t have a problem with triggers. They get the job done when you need to implement business logic in a hurry, and you’re not allowed to change the...

Parsing JSON Data In SQL Server

Microsoft added support for JSON data beginning with SQL Server 2016. JSON is an open-standard file format consisting of attribute–value pairs and array data types. It is commonly used...

Using IGNORE NULLS With SQL Window Functions to Fill Gaps

I found a very interesting SQL question on Twitter recently

Removing multiple patterns from a string

Recently one of my clients had a request that was a challenge to do effectively. I don’t think it’s a very common requirement but I still decided to blog...

When Window Functions are Too Slow

Bert Wagner shows a scenario where a window function ends up performing poorly: If you’ve used FIRST_VALUE before, this query should be easy to interpret: for each badge Name, return the...