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....
The...

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...
The...

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...

Get the Datetime