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Category: Syntax

Bad Query Signals

Published 2026-07-14 by Kevin Feasel

Mala Mahadevan takes advantage of an extra week:

I just managed to get a post in for this landmark T-SQL Tuesday, hosted by Brent Ozar. Brent was kind enough to keep the submission window open for two weeks instead of the usual one, and I was able to sneak a post in last – minute.

His invitation is to write about the things that immediately stand out as “bad signs” when reviewing a SQL query.

Click through for Mala’s list. It’s a good list. While some items Mala calls out are defensible and quite reasonable, there are some of them (such as a LEFT OUTER JOIN whose columns show up in the WHERE clause for filtering) that are simply not.

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Checking Query Options from Query Store

Published 2026-07-13 by Kevin Feasel

Michael Bourgon sets ANSI_PADDING:

We know that SQL Server can cache multiple query plans for the same query based on the SET_OPTIONS for that query, and that SSMS doesn’t have the same options as the standard library. (https://www.sommarskog.se/query-plan-mysteries.html). He even includes a chart!

My initial comment was “Michael Bourgon sets XACT_ABORT” but that’s actually not one of the list, so I had to change it for the sake of correctness even though I think it was funnier in its original guise.

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Red Flags in Query Design

Published 2026-07-09 by Kevin Feasel

Thomas Williams has a list:

Nowadays I look after 3rd-party databases more than internally-developed ones, so I accept there’s a whole lot of ex-best practices, vendor preferences, and possibly shortcuts in queries I might come across – whether it’s a poorly-performing query, a blocker, or an error.

(Although, when I developed software more frequently, I was guilty of all the gripes below. My start in SQL, last century, was poring over a big yellow “For Dummies” book. I was the dummy.)

Click through for the list. I particularly hate tibbling, a rather derisive term for the malformed version of Hungarian notation. This would just lead me down a rant about how systems Hungarian notation was a mess, whereas apps Hungarian notation can be useful in certain circumstances. Tibbling provides no semantically valuable information, which is why I dislike it so much.

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T-SQL Code Smells

Published 2026-07-09 by Kevin Feasel

Rob Farley has a few:

I feel like I should preface this with a disclaimer. I added “potentially-” to the title, because there are many queries that might seem bad but can actually perform just fine. There are queries that on the surface can be great, but are nasty without a particular index, and there are queries that make me cringe a little when looking at them, but are actually okay. Brent Ozar is asking about signs of bad code for this month’s T-SQL Tuesday (the 200th – and I have a response for all 200 if you look back through my history of posts), and he wants us to write this for 2004 Brent, rather than 2026 Brent.

Click through for what Rob has come up with. I agree with all of Rob’s examples and do appreciate his usage of the APPLY operator as a way of solving one common problem.

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Traits of Sketchy Queries

Published 2026-07-09 by Kevin Feasel

Louis Davidson has a list of red flags in code:

I still feel like garbage, so I decided just a simple list would do. I will also preface this by saying each item could include “without a coherent comment.”

Everything on this list fills me with dread unless I read someone say: “Such and such was needed because the optimizer wouldn’t….” and then I at least know why they believed needed it.

Click through for Louis’s list. Most of these aren’t bad things per se, but they do serve as signs of a potential deeper issue.

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Red Flags in Database Code

Published 2026-07-08 by Kevin Feasel

Tom Zika has a list and starts with AI-generated code:

This one didn’t exist three years ago. Now it’s the first thing I look for.

To be clear, I’m not anti-AI. If the AI wrote clean code, I probably wouldn’t even notice. The red flag isn’t that AI generated it – it’s the patterns that give it away. I recently saw a real case where someone needed to update a set of values. Simple enough, right? Here’s what the AI-generated solution did:

Click through for a laugh, as well as several other red flags.

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Proper Disdain for ANSI-89 Join Format

Published 2026-07-08 by Kevin Feasel

Andy Brownsword has it together:

It’s a legacy pattern, and thankfully it’s rare to see these in the wild nowadays.

The legacy OUTER JOIN syntax (*= and =*) which used to accompany these was deprecated, and finally removed in *checks watch* SQL Server 2012, so that’s one less reason to see the aging syntax.

Every time I see this format, I despise it. Andy explains exactly why. We’ve had better options for more than 30 years, yet people still choose to write code this way.

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What’s Common in Regular Expressions

Published 2026-06-25 by Kevin Feasel

John Cook muses on regular expression libraries:

The most frustrating aspect of regular expressions is that implementations vary. Features supported in one tool may not be supported at all in another tool, or they may be supported with slightly different syntax.

I learned regular expressions in the context Perl, a maximalist regex environment. This led to frustration when features I expect to work are missing [1]. One way around this is to use Perl analogs of other tools, but this is very non-standard. I want to be able to send colleagues and clients code that works out of the box.

Click through for some thoughts about the lowest common denominator for what products tend to support around regex. This is one of several tricky things when working with regular expressions: you may know a great way to solve a specific class of problem, but does the particular engine you’re using actually support that method?

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