Category: Syntax

Brent Ozar has an update:

Back in March 2025 when Microsoft first announced that REGEX support was coming to SQL Server 2025 and Azure SQL DB, I gave it a quick test, and the performance was horrific. It was bad in 3 different ways:

1. The CPU usage was terrible, burning 60 seconds of CPU time to check a few million rows
2. It refused to use an index
3. The cardinality estimation was terrible, hard-coded to 30% of the table

Read on to see what has changed. It’s obviously not perfect, but just as obviously is much better than what Brent saw in Azure SQL DB at the time.

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Tomaz Kastrun continues an advent of SQL Server 2025. Day 8 looks at a pair of regular expression-related functions:

Continuing with SQL Server 2025 T-SQL functions for Regular Expressions for in string and count functionalities.

And Day 9 hits two more:

Last two functions in the family of new T-SQL functions that were shipped with RegEx, are REGEXP_MATCHES() and REGEXP_SPLIT_TO_TABLE().

Read on to see how all four of these work.

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Tomaz Kastrun has been busy with this year’s advent of SQL Server 2025 blog posting. Catching up, Tomaz first looks at base-64 encoding and decoding:

SQL Server 2025 introduces a new T-SQL functions for BASE64 varbinary expressions. The first function returns base64-encoded text (BASE64_ENCODE() ), respectively for BASE64_DECODE().

BASE64_ENCODE converts the value of a varbinary expression into a base64-encoded varchar expression.

BASE64_DECODE converts a base64-encoded varchar expression into the corresponding varbinary expression.

I really like this, by the way. Base-64 encoding is quite useful for web transmissions, so having a place to generate that output easily is nice.

Second up is REGEXP_LIKE():

SQL Server 2025 introduces a new T-SQL functions for Regular Expressions (RegEx).

With multiple RegEx functions, the LIKE function indicates if the regular expression pattern matches the string or is in a string. The function is REGEXP_LIKE() that will do the job.

And third, we have REGEXP_SUBSTR() and REGEXP_REPLACE():

Continuing with SQL Server 2025 T-SQL functions for Regular Expressions for replace and substring functionalities.

Click through for Tomaz’s thoughts on all five of these functions.

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Louis Davidson is lost in translation:

The data I am working with sometimes has people with multiple parts to their name (Mary Jo, Cindy Lou) etc, or sometimes Fred/Joe, Mary and Jack, Mary & Jack, or what have you. My goal was to turn these names into little delimited lists that I could parse on a space character with STRING_SPLIT and there were a “few” of these cases. This was the code I had arrived at when I reached the “good enough” stage of my coding.

Louis had 19 nested REPLACE() calls, but Certified Good Guy Erik Darling shows him the way.

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Tomaz Kastrun’s advent of blogging this year is on SQL Server 2025 and the latest post involves the PRODUCT() function:

SQL Server 2025 introduces a new T-SQL function, called PRODUCT(). The function returns the product of all the numeric (and only) values in the expression. NULL values are ignored and DISTINC values can be set.

Distinct product is an interesting one.

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Jared Westover wants a range:

In this article, we’ll explore the concept of framing in window functions. We’ll compare the differences between the ROWS and RANGE clauses and discuss when to choose one over the other. We’ll also highlight common pitfalls of framing and whether it applies to all types of window functions. By the end, you’ll better understand how framing works with window functions, making it seem less complex.

Click through for a primer on frames in window functions. Admittedly, if I were writing this article, I’d toss out most of the “pitfalls” section, as pitfalls 2 and 3 aren’t particularly relevant or pitfall-y (because SQL Server always defines a frame on a window function if you don’t). Instead, I’d add that there are some annoying limitations on RANGE frames, where the ANSI SQL standard allows you to use intervals like date or time when defining frames, so you can get records ranging from three hours ago to right now, for example.

But that said, it’s a good overview if you’re fairly new to window functions.

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Rajendra Gupta uses a reducer function:

SQL Server 2025 includes new features and enhancements. In the previous SQL Server 2025 tips, we have explored many new features. Have you explored the new Product() function? If not, this will walk you through the Product() function with several examples.

Read on to see how PRODUCT() works and how thoughtful the development team was around supporting window functions as an aggregate function.

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Hristo Hristov makes a call:

One highly anticipated new feature in SQL Server 2025 is the ability to call an external REST API endpoint from the database server itself. This new feature opens the door to new data integration scenarios and delivers on the promise to “bring AI closer to data.” What are the steps to follow if you want to use this new feature?

I expect to see two things from this. First, some percentage of developers will abuse it and cause performance problems in the database. Second, some percentage of database administrators will panic about this and try to prevent its use even when it makes sense.

But hey, at least this time, they didn’t use the term “unsafe” to describe something DBAs don’t understand and thus cause a widescale panic.

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Louis Davidson shows off some more of the power of regular expressions:

One of the practical uses of RegEx is more powerful filtering. One of the projects I am working on, (very slowly) is sharing some SQL utilities on GitHub, Utilities like looking at the metadata of a table, searching for columns, database sizes, etc. I usually use LIKE to filter data, which lets me simply use an equality search, or I can also do a partial value search when I don’t know exactly what I am looking for.

LIKE is quite useful but, as Louis points out, it does have its limits. And in those limits is where regular expressions do so well.

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