SQLServerFast

T-SQL Tuesday #111: Why, tell me why

Hugo Kornelis
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Time flies. It feels like the new year has just started, and yet we’re already at the second T-SQL Tuesday of the year. Our host this February is Andy Leonard (b|t), and his assigned topic is, simply: Why? Or rather: What is your why? What motivates you, what makes you tick? And most of all: What makes you do the things you do? The Execution Plan Reference I do a lot of things. I have a one-person consultancy business, I have a wife and kids, I have a personal life with several hobbies, and I could talk about my motivation…
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Plansplaining, part 10. Just passing through

Hugo Kornelis
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Welcome to part ten of the plansplaining series. Each of these posts takes an execution plan with an interesting pattern, and details exactly how that plan (or pattern) works. In this post we will look at a query and execution plan that may appear perfectly normal and unexpected at first sight, but that has some perhaps confusing execution counts. Sample query The sample query below will (as almost always) run in all versions of the AdventureWorks sample database. It returns a list of all staff, and for people that have a sales-related job title it adds the total of sales…
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SQL injection

Hugo Kornelis
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One of the many sites where I occasionally answer database-related (and sometimes other) questions is Quora – also known as “yet another question and answer site because we all know that what the world really needs is yet another question and answer site”. On that site (and probably many others), some topics just keep resurfacing. One of those “evergreen” topics is SQL injection. The questions on this topic are not all the same, but they all do fall into a few broad categories. So instead of repeating the same reply over and over again, I have decided to write a…
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Collation change script

Hugo Kornelis
29 Comments
WARNING: The script presented in this post was for a specific situation at a specific client. It was not intended to be complete, and it is not actively maintained. Several people have suggested improvements in the comments, and Erland Sommarskog has written a long article where he presents a more refined version. Please check which version works best for you, and test with care! Normally when I blog, I spend a lot of time making sure that get as close to perfection as I can. This post is an exception. The problem I am talking about is too far out…
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Off Topic: Charity and snooker

Hugo Kornelis
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So this will be a very unusual post for this blog. It will be completely off topic. One of the things I do in my spare time is to play snooker. Mind you, I am not good at the game. But I enjoy it, and it’s a nice break from sitting at my laptop. Marathon So why do I share this tidbit about my personal life? Why do I think anyone cares? The reason is that I need some help. Next month, on February 15 and 16, 2019, I am participating in a 24-hour snooker marathon. And with my participation…
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T-SQL Tuesday #110 – “Automate All the Things”

Hugo Kornelis
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It is once more the second Tuesday of the month, better known as T-SQL Tuesday. This month, we got our writing assignment from Garry Bargsley (b|t). He asks us to write about automation: what automation are we proud of or do we want to complete, and using what technology? However, I found that I was more triggered by the title of his request post than by the content, so I’ll allow myself the liberty of applying a very loose interpretation of the topic. All the things? Garry titled his invitation “Automate All the Things”, and I plagiarized that title because…
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Looking back to 2018

Hugo Kornelis
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We are approaching the end of 2018. It is December 30 as I start writing this (I’ll probably finish and publish it December 31), traditionally a time to look back at the past year. I often refrain from doing what everybody does because a certain date is on the calendar (my dad would sigh and suggest that I’m still not over puberty, and he’d probably be right). But in this case I’ll make an exception. For me, 2018 was mainly the year I started building my own website. The site where I publish my blog posts, but more important: the…
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Plansplaining, part 9. Recursive CTEs

Hugo Kornelis
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I had to skip three months, but finally it is here: part eight of the plansplaining series. Each of these posts takes an execution plan with an interesting pattern, and details exactly how that plan works. I am pretty sure that (almost) everyone reading this blog knows that a CTE (Common Table Expression) is an independent subquery that can be named and then referenced (multiple times if needed) in the main query. This makes CTEs an invaluable tool to increase the readability of complex queries. Almost everything we can do with a CTE can equally well be done by using…
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More information in execution plans

Hugo Kornelis
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Troubleshoorting performance issues can be hard. Having as much information available at our fingertips does not magically make this easier but it does at least save us the burden of having to collect that information from other places. That’s why I like how much extra information Microsoft has been adding to execution plans in recent releases. During this year’s PASS Summit, I went to a session presented by Pedro Lopes and Joe Sack. Pedro explained in his half of the session that Microsoft has the goal of making sure that everything we need for troubleshooting will be available in the…
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T-SQL Tuesday #106: How to use triggers and not be sad

Hugo Kornelis
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The T-SQL Tuesday subject for September, chosen by Steve Jones (b|t), is to write about an experience I had with triggers. I decided to apply a very loose interpretation of his assignment and write more about triggers in general. Undeserved hate My very first SQL Server related job was quite unusual. I was added to a team that developed software using a code generator. We had to define business rules (such as constraints and derivation rules) on top of a conceptual information model for the company. The tool would then generate T-SQL code to support and implement those rules. The…
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Hugo Kornelis

Married, father of 2 children.

Awarded 13x MVP (2006-2016; 2019-now), in the areas SQL Server and Data Platform.

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