Category: SQL Server

If you’re worried about interviewing for a SQL Server job, here’s some advice from the former head of an IT department on what matters (along with examples from the three critical areas where you need to have answers ready). As an instructor for Learning Tree’s Querying SQL Server 2014 and 2016 courses, I’ve worked with […]

More Analytic Excitement in SQL Server 2017 Last week (the third week in April 2017) Microsoft released its Community Technology Preview 2.0 for SQL Server vNext, more often referred to as simply “SQL Server 2017”. Among the many new features of interest to business intelligence analysts, data scientists, and machine learning aficionados is support for […]

Part III – A Look at a “Physical” Subquery Perhaps I am being a little loose in my terminology, since there really isn’t a query operator called “subquery”. When I say “physical subquery” I am referring to those correlated subqueries where the subquery portion must be executed again and again, once for every row returned […]

Part II – The Table Spool In the previous installment, we looked at a very simple logical subquery that SQL Server executed as a physical join. We shall now take a look at a somewhat more complicated query and see what SQL Server does with it. In this query, we would like to get a […]

As a part of our continuing study of SQL Server query plans, we’re going to take a look at some subqueries. This is particularly important, since subqueries are the subject of some fair amount of folklore, and it is important to separate fact from myth. It’s not uncommon to hear someone say “Joins are better […]