A Fine Slice Of SQL Server
Aaron Bertrand notes some T-SQL improvements:
A few of the most useful changes I’ve been able to play with in SQL Server 2022 so far:
– GREATEST / LEAST
– STRING_SPLIT
– DATE_BUCKET
– GENERATE_SERIES
In this tip, I’ll explain each one, and show some practical use cases.
Click through for more information. I particularly like GREATEST() and LEAST() but GENERATE_SERIES() could be very useful as well. Some of this stuff was first made available in Azure SQL Edge.
Kenneth Fisher doesn’t like this database and wants to move to a new one:
This is one of those things that on hindsight was a stupid problem, but still cost me hours and a major headache. So I thought I would share the story of my headache with you.
A few weeks ago I was working on some dynamic SQL that hit multiple databases. Not a huge issue. I do lots of dynamic SQL.
But it didn’t quite work out the way Kenneth initially envisioned. Read on for the full story.
Comments closedJoe Billingham explains why you can’t do that thing you want to do:
So, you have just written a query, hit execute and you have encountered an error: Invalid column name ‘[column name]‘.
The column you’ve used in your WHERE clause cannot be identified by its alias. You’ve defined it at the top of the query and used it fine previously as your ORDER BY condition, so why can’t the engine recognise it?
Read on for the answer. This is why some people I know have wanted a SQL-like language which runs in order of execution, so a query would start with the FROM clause rather than the SELECT clause. Languages like KQL do work that day, so there are examples in the wild.
Comments closedErik Darling tries something out:
I think it was sometime in the last century that I mentioned I often recommend folks turn on Forced Parameterization in order to deal with poorly formed application queries that send literal rather than parameterized values to SQL Server.
And then just like a magickal that, I recommended it to someone who also has a lot of problems with Local Variables in their stored procedures.
They were curious about if Forced Parameterization would fix that, and the answer is no.
Shot down by the third paragraph of the intro. That’s rough. Still, click through for the demo.
Comments closedChad Callihan shows off a good use of aggregate functions and the CASE statement:
Have you have been tasked with pulling multiple counts from the same table? Maybe you need to find how many records have a value for a column and how many are NULL. Or maybe you need to see how many records are true and how many are false.
It’s simple enough to run a query to count one set of criteria, run another query for the second set of criteria, and combine them when sending your results. Did you know you can get multiple counts with one query?
Here’s an example of how using COUNT and CASE can speed up your day.
Click through for an example. I mildly disagree with Chad’s conclusion that this is something you’ll rarely do—the more you work with reporting and analytical queries, the more you’ll appreciate this.
Comments closedEd Pollack shares several good T-SQL tips to simplify code:
While trying to solve the data challenges an organization throws our way, it is often easy to get buried in large, complex queries. Despite efforts to write concise, easy to read, maintainable T-SQL, sometimes the need to just get a data set quickly results in scary code that is better off avoided rather than committed.
This article dives into a handful of query patterns that can be useful when attempting to simplify messy code and can both improve query performance while improving maintainability at the same time!
Click through to learn more. I use most of those tips to great effect (though don’t often have need to hit some of the DMVs Ed mentions).
Comments closedDaniel Hutmacher mixes separators with regular characters:
Suppose you have a delimited string input that you want to split into its parts. That’s what STRING_SPLIT() does:
DECLARE @source nvarchar(max)='Canada, Cape Verde, '+ 'Central African Republic, Chad, Chile, China, Colombia, Comoros';
SELECT TRIM([value]) AS[Country]FROM STRING_SPLIT(@source, ',');Simple enough. But delimited lists are tricky, because the delimiter could exist in the name itself. Look for yourself what happens when we add the two Congos to the list:
Daniel has a clever solution to the problem.
Comments closedSteve Jones shows off a good use case for window functions:
Recently I was looking at some data and wanted to analyze it by month. I have a goal that is set for each day and then an actual value. I wanted to know how I was tracking against the goal, as a running total. If my goal is 10 a day, then I ought to actually get to 10 the first day, 20 for the second day (10 + 10), etc.
Read on to see how Steve solved the problem.
Comments closedMichael Bourgon notices a difference between Azure SQL DB and Managed Instance/box product:
I was trying to get some Xquery parsing working, and ran into a weird error:
"CONDITIONAL failed because the following SET options have incorrect settings: 'QUOTED_IDENTIFIER'"Weird. Doubly so because this code has worked on-prem for a decade, and the Managed Instance is running it now.
Read on for the solution.
Comments closedTomaz Kastrun explains how to combine data in two languages:
Merge statement in R language is a powerful, simple, straightforward method for joining data frames. Nevertheless, it also serves with some neat features that give R users fast data wrangling.
I will be comparing this feature with T-SQL language, to show the simplicity of the merge method.
Click through for the comparison.
Comments closed