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Category: Syntax

Materializing Lake Views in Microsoft Fabric

Published 2025-08-27 by Kevin Feasel

Sairam Yeturi reduces ETL and ELT requirements:

Organizations often face challenges when trying to scale analytics across large volumes of data stored in centralized SQL databases. As business teams demand faster, more tailored insights, traditional reporting pipelines can become bottlenecks. By adopting Lakehouse architecture with Microsoft Fabric, business groups can mirror their SQL data into OneLake and organize it using the Medallion architecture—Bronze, Silver, and Gold layers. Materialized lake views play a crucial role in this setup, enabling automated, declarative transformations that clean and enrich data in the Silver layer. This empowers teams to build reliable dashboards and AI-driven insights on top of curated data, all while maintaining performance, governance, and security on a scale.

In this post, we will cover how enterprises can use materialized lake views to streamline data orchestration and enhance data quality, monitoring across silver and gold layers, while mirroring their SQL DB tables to Fabric in the Bronze layer.

The best use case for this is a scenario in which your underlying data is already essentially in a star schema or at least easily transformable into one, and you have no interest in modifying the data in the view directly. Do read the limitations before digging in, though, as there are some big ones.

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Tracking Time Series Rates of Change in SQL Server

Published 2025-08-26 by Kevin Feasel

Rick Dobson wants a measure of variation:

This tip presents a brief introduction to Common Table Expressions (CTE), along with a few references for those seeking additional details on CTEs beyond those described and demonstrated here. We will examine CTEs that are defined by either one or two SELECT statements. Additionally, we will provide a demonstration of a recursive CTE. All the examples illustrate how to process time series datasets with CTEs.

Click through for the tip.

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Row and Range Frames in Window Functions and Batch Mode

Published 2025-08-25 by Kevin Feasel

Erik Darling covers how your window frame (that is, ROWS or RANGE in the window function definition) can affect batch mode.

Erik looks at a classic performance difference between ROWS and RANGE, as well as what batch mode does to even the score. This is particularly nice because ROWS and RANGE both have their utility and focusing on one versus the other for performance differences can lead to awkward development practices to get around a window spool.

Erik also focuses primarily on batch mode on rowstore, so keep in mind the minimum requirements for it: 131,072 (or 2^17) rows in at least one table in the query, at least one operator that benefits from batch mode (which we’d cover in the window function), at least one input of the batch with 2^17 rows, and where the batch mode cost is lower than the row mode cost.

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Pattern Matching with REGEXP_LIKE() in SQL Server 2025

Published 2025-08-22 by Kevin Feasel

Koen Verbeeck writes a regular expression:

I need to do some data validation in our SQL Server database. However, the validation rules are too complex for the T-SQL LIKE function, and I can’t seem to get it done either with PATINDEX or something similar. I’d like to use regular expressions as they’re more powerful. SQL Server 2025 now has a regex function regexep_like to use regular expressions.

Read on for some examples, advice on validating e-mail addresses, and more.

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Multi- and Single-Line Regular Expression Processing in SQL Server

Published 2025-08-21 by Kevin Feasel

Louis Davidson continues a series on regular expressions in SQL Server:

There are currently only 4 flags that SQL Server supports and they are used to change some of the fundamental ways that the expressions are applied. These flags are:

i – insensitive
c – case sensitive
m – ^ and $ match end of line, not entire string
s – single line, dot matches newline

In Part 6, I covered i and c, no[w] let’s do m and s. These flags are not ones I expect to use all that often, but they are definitely useful to know.

Read on to see how they work, as well as some of the issues Louis ran into along the way.

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Flags in SQL Server Regular Expression Functionality

Published 2025-08-14 by Kevin Feasel

Louis Davidson continues a series on regular expressions:

In this week’s sixth entry of my learning RegEx series, I am going to do two last intro entries for a while, this one on case sensitivity, and another on multi and single line searches. After this I will move into all of the functions that are available in SQL Server 2025 and Azure SQL (and I will come back if I learn any additional things that we need to cover either right after that, or anytime I learn something new I want to share about RegEx).

Read on to see which flags SQL Server currently supports. Of those, Louis tries out a pair.

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SQL Server Regular Expressions with Multiple Matches

Published 2025-08-07 by Kevin Feasel

Louis Davidson has popped and therefore cannot stop:

The goal of this week’s entry is specifically to show how to see how multiple matches can be viewed using SQL Server’s RegEx, specifically to make the examples clearer (especially in the upcoming entries).

There are several functions that you can use where multiple matches are used as part of the output:

Click through for that list and several examples of relevant functions in action.

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Thoughts on Views

Published 2025-08-06 by Kevin Feasel

Joe Celko shares some thoughts on views, as well as recursive common table expressions:

VIEWs are an undervalued and underused feature in SQL. They basically consist of a query that has been given a name, and a parameter list, so can be used like an inline macro. Technically, you’re supposed to think of it as a virtual table. 

The idea of an inline macro or inline function goes way back to the first versions of Fortran and later BASIC. Depending on the product, the syntax might look like this: FN DOUBLE (N) = (N + N). You had to give the name of the Macro, a simple optional parameter list, assignment operator, usually an =, and the text of the computation. It was often important to put parentheses around the body of the macro, or to have a compiler that would do this for you. 

Read on for the article and a platform-agnostic coverage of views. My problem with views is that developers try to use them to cover a lot of ruin and then they ask why such a simple SELECT * FROM Something query is so slow.

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Regular Expression-Based String Splitting in SQL Server 2025

Published 2025-08-05 by Kevin Feasel

Aaron Bertrand splits a string:

SQL Server users have been asking for native regular expression support for over two decades. There are third-party Common Language Runtime (CLR) modules that offer this functionality, but these can be complicated to install and simply aren’t possible in some environments. I want to split a string using a regular expression instead of a static string. Will that be possible in SQL Server 2025, without CLR?

Must not rant about CLR. Must not rant about CLR. Must not rant about CLR. (By the way, if you ever catch me in person, get me going about how CLR got the short end of the stick and how the ‘modern’ forms of the Common Language Runtime in SQL Server are not great.)

Aaron tries out a function built into SQL Server that allows you to split strings into result sets using a regular expression to perform the splitting, and shows off some of the more complicated scenarios that this can solve over a normal STRING_SPLIT() function call.

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