Category: Uncategorized

Brent Ozar is working on a series of SQL interview questions.  Today’s is “talk me through this query:”

Last month’s post “For Technical Interviews, Don’t Ask Questions, Show Screenshots” was a surprise hit, and lots of folks asked for more details about the types of screenshots I’d show. Over the next few weeks, I’ll share a few more.

Normally I’d show this query as a screenshot, but for easier copy/pasting into comments, I’m showing it as code here.

I’d say to the job candidate, “You’ve been asked to take a quick look at this code as part of a deployment. Explain what the business purpose of the code is, and tell me if there’s anything that concerns you.”

I like where Brent is going with this series and plan to incorporate some of these into my in-person interviews.

Scott Guthrie and Satya Nadella are hosting a SQL Server 2016 live event starting at 10 AM Eastern (via Scott Guthrie).

Yeah, it’s a marketing event, but there might be something interesting and exciting to come out of it.

Kenneth Fisher on varchar versus nvarchar:

In any study of Data Types in SQL Server you are going to have to look at the various string data types. One important component is the difference between nChar vs Char and nVarChar vs VarChar. Most people reading this are probably thinking “Well that’s ridiculously easy.” If you are one of them then I want you to read these two facts about these data types.

	Char and VarChar	nChar and nVarChar
Stores	ASCII	UNICODE
Size	Always one byte per character.	Always two bytes per character.

One of these is incorrect. Do you know which one?

The correct answer is “both are wrong.”  Then you get into debates about what a “character” is, how certain languages (like Hebrew and Arabic) have layers of modifiers which modify semantic context, etc. etc.  Strings are probably even harder than dates.

Tim Radney uses iperf to perform network load testing:

Poor network performance can be a silent killer for application performance and my personal experience has shown this to be the case on many occasions. Often an application would start having performance issues and the application engineer would say that the application server looks good and starts to point their finger at the database. I would get a call to look at the database server and all indications showed that the database server was in good health (and this is where monitoring for key performance indicators and having a baseline helps!). Since the application and database teams were saying everything was good, we would ask the network team to check things out. The network team would look at a few things and give the all clear on their side as well. Each team troubleshooting and reviewing their respective systems took time, meanwhile the application performance was still suffering. The issue would then get escalated until all the teams would be asked to join a conference bridge to troubleshoot together. Eventually someone would start a deeper network test and determine that we either had a port saturation, routing, or some other complex networking issue. A few clicks or changing something on their end would eventually resolve the application slowness.

iperf is a nice tool for checking to see if your network throughput looks reasonable.

Doug Lane has an outstanding post on the types of equipment you should look at if you’re getting into technical presentations:

Your choice(s) here will drive what equipment you need to buy in order to produce a high-quality video on a reasonable budget. You don’t want to overspend on lighting and camera equipment if you’re never going to be shown bigger than a 240×180 pocket in the corner. Likewise, you may not need a USB microphone if you’re going to shoot mostly studio video.

As someone thinking about getting into podcasting and webcasting, this is a top-notch set of advice.

Phil Factor generates feast days:

I’ve been determined to produce a SQL Expression that was able to tell you when all the feasts and saints days are. In the following example, I’ve only put the major feast days that were generally celebrated in Britain before the reformation, but it is very easy to add or take away what I’ve given you to taste.

A fitting topic for America’s premier feast day.

Curated SQL will not be taking Thanksgiving off.  To compensate for the pace of blog posting activity usually drops around Thanksgiving, I’ll link to a few classic articles.  That way, even if you’re in the office, you’ll have something to occupy that extra time.