Development

You’ve been working with Microsoft SQL Server for yeeears, and you’re pretty confident that you know how to write a query. So when I tell you about a book called T-SQL Fundamentals, you’re all, “nah, man, I got this covered.” You are incorrect. Sure, the first 5 chapters of the book are about 1-2 table…

In a programming language like C# or Java, you tell the computer what to do, in order. Get the customers from California, then get their invoices, then sum the total. SQL, on the other hand, is a declarative language where you declare the shape of your result set: Get the total sales from Californian customers.…

This week’s series on error handling has been an eye opener for many of us. We’ve laughed. We’ve cried. We’ve screamed in horror. We’ve read the documentation. I don’t blame you. This is a really confusing topic, and for many of us, it’s the first time we’ve actually looked at the mechanics of how transactions,…

CAN YOU BELIEVE THAT HOT MESS IN YESTERDAY’S POST?!? I know, right? You thought that by combining try/catch with a transaction, you’d get robust error handling.  Instead, you ended up with half the tables populated, and a leftover open transaction. You’d already forgotten Tuesday’s post in which I pointed out that TRY/CATCH doesn’t catch low…

In yesterday’s epic cliffhanger, you might have been shocked to discover that a plain ol’ transaction does not solve our problem – and in fact, it makes things worse. With yesterday’s code, we still got rows inserted into the Parent table, no rows in the Child table, and a nasty surprise that our session will…

Let’s say we have two tables, Parent and Child, and we need to guarantee that they both get populated at once. We’ll write a single stored procedure to do both inserts: DROP TABLE IF EXISTS dbo.Parent; DROP TABLE IF EXISTS dbo.Child; CREATE TABLE dbo.Parent (ID INT IDENTITY(1,1), DateAdded DATETIME2); CREATE TABLE dbo.Child (ID INT IDENTITY(1,1),…

David Tovee asked a great question in yesterday’s Mastering Query Tuning class. He asked his fellow students, “How many of you actually use TRY/CATCH?” I turned it into a Twitter poll because I wanted to check a wider audience: When the developers at my company write new queries, they use TRY/CATCH and exception handling: —…

When you’re working with T-SQL, you’ll often see SET NOCOUNT ON at the beginning of stored procedures and triggers. What SET NCOUNT ON does is prevent the “1 row affected” messages from being returned for every operation. I’ll demo it by writing a stored procedure in the Stack Overflow database to cast a vote: CREATE…

It’s hard to set absolute rules about, “Feature X should absolutely never be used.” However, there are some features that set off alarm bells when I see them. Usually, when I start asking more questions about when we’re using those particular features, I get answers of, “Oh, I didn’t know that was a problem.” As…