This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Developer Level: Intro
Question:
You need to filter rows being returned by a query.
When should you use a HAVING clause rather than a WHERE clause?
Answer:
A WHERE clause is used to filter the rows from the source (usually a table).
2025-05-24
Over the years, I’ve had a surprising number of questions on how to output all the data in a table as a series of INSERT statements. SQL Server Management Studio has had the ability to do this for a long time. Here’s an example.
In Object Explorer, I’ve expanded the WideWorldImporters database, then expanded Tables. Where people come unstuck is they right-click the table, and look at the scripting options:
2025-05-23
I recently wrote about the most common misconfiguration that I see for linked servers. It greatly affects performance.
The second most common linked server misconfiguration is related to security. I can’t tell you how many times I’ve seen this when reviewing SQL Server systems for clients.
The issue you need to consider is that when your local SQL Server connects to the remote SQL Server, which identity is used for the connection?
2025-05-22
I’ve mentioned a number of times how useful I think the Object Explorer Details panel is in SQL Server Management Studio.
One option in that panel that might not be so obvious is the sorted navigation. Here’s an example.
I’ve opened the WideWorldImporters database in Object Explorer, and clicked on the Tables node:
I then hit F7 to open the Object Explorer Details pane and clicked the Name heading to sort the table list. I like it ascending so you might need to click it twice:
2025-05-21
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Administrator Level: Medium
Question:
You are considering adding an index to a table.
You have heard that adding indexes slows down UPDATE commands.
Does adding an index always slow down updates? If so, why? If not, why not?
2025-05-20
If you are working with databases with large numbers of objects, the contents of Object Explorer in SQL Server Management Studio can start to become a bit overwhelming. I wish it offered an option to group by schema. That would be helpful.
But you can at least filter by things like schema, when you need to work with a specific set of objects. You’ll notice that if you click on the database name, that the filter in the toolbar is grayed out, but if you click on a node below that like Tables, you can click on the toolbar filter icon. You can also right-click the node and choose to filter:
2025-05-19
I’ve recently been reading a few articles and discussions around linked servers, and I’ve noticed two things:
I do think they’re pretty easy to configure, but they’re also easy to configure badly.
And that leads us to the main cause of the second issue: performance.
I review the configuration of a lot of systems, and the primary issue I see with how linked servers are configured, is that the Server Option Collation Compatible has been left at the default value.
2025-05-18
I started working with SQL Server in 1992, but all through the 1980’s and 1990’s, I was also working with Progress 4GL. I thought it was the best of the character-based 4GLs but unfortunately, they did a poor job of migrating to Windows and we decided to stop using the product.
One thing that I used to love with Progress though is that the metadata for each column in the database was much richer than what is present in SQL Server. In fact, Microsoft Access was probably closer to it in that regard. It’s something I really missed when moving to SQL Server. In Progress, when I defined a column, I could also define things like:
2025-05-17
This is a post in the SQL Interview series. These aren’t trick or gotcha questions, they’re just questions designed to scope out a candidate’s knowledge around SQL Server and Azure SQL Database.
Section: Administrator Level: Medium
Question:
Your database application has been suffering from signficant blocking issues.
One developer has suggested enabling RCSI for the database.
If you do that, what’s different about how the database would operate?
What code changes are needed to use it?
2025-05-16
One thing that has annoyed me for a long time is why applications and systems make it so hard to disconnect yourself from a tenant that you don’t control. Here are two examples:
The first one that’s frustrated me lately is Stripe. Setting up your own account is straightforward, and leaving isn’t too hard.
But they have a service called Stripe Connect. In this case, the account is basically set up for you by a vendor you are dealing with, essentially on your behalf.
2025-05-15
