Category: Syntax

Chad Callihan obliquely reminds us to create those unique constraints (by way of unique indexes):

Did you know there is more than one way to set a variable in SQL Server? You can actually set a variable without using “SET” at all. Let’s look at an example that shows how setting a variable with SELECT can cause a headache when dealing with identical values.

Click through to see the problem in action. One way around this if you do know you are dealing with duplicates and need a specific one is to SELECT TOP(1) with an appropriate ORDER BY clause, just as you would if variable assignment weren’t on the table.

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Erik Darling shows off one way to search for strings in T-SQL:

First, I want to advise you to avoid doing things as much as possible like this in T-SQL. Use CLR, if you can. Or do it outside of your really expensive database server.

You know, rational choices.

YOU’RE NOT MY REAL DAD, ERIK!

Do read the post, especially because it’s not just slapping a LIKE '%x%' on there and calling it a day.

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Chad Callihan protects the reputation of SELECT *:

There are plenty of scenarios where using SELECT * can be an issue. Using SELECT * with EXISTS isn’t one of them.

When using EXISTS and SELECT * together, SQL Server is smart enough to realize what you’re doing and knows you don’t care about what’s in the SELECT.

Read on for an example. I’ve trained myself (been trained?) still to use SELECT 1. The reason is, I know SELECT * works exactly the same way but the benefit of using SELECT 1 is that doing this consistently allows you to do a search for SELECT * in your code base to find actual perpetrators (people writing queries expecting to return the entire result set and which may be susceptible to performance problems or future maintainability problems). Using SELECT 1 in the EXISTS clause means you get fewer false positives in that search as a result.

That said, Joe Celko chimes in to provide some of the history behind SELECT * as the convention for references in the EXISTS clause.

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Hasan Savran starts bucketing:

The Date_Bucket function is introduced in Azure SQL Edge which is mainly used by IoT devices. This useful function returns the date-time value corresponding to the start of each date-time bucket from the timestamp defined by the origin parameter, or the default origin value of 1900-01-01 00:00:00.000. In other words, it lets you arrange data into groups that represent fixed intervals of time. SQL Server 2022 includes this useful function in its database engine.

Results of Data_Bucket might be confusing, Let’s look at its syntax first.

Hasan is quite right here: the results of DATE_BUCKET() are not intuitive, though they do make some sense…eventually…

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Hasan Savran takes us through a rather useful pair of functions:

GREATEST and LEAST functions are available in Azure SQL and SQL Server 2022. GREATEST returns the maximum value from a list of expressions. LEAST returns the minimum value from a list of expressions. 

     The Highest number of expressions you can pass to these functions is 254. All expressions must be comparable for these functions to work. For example, SQL Server can automatically convert the following string to an integer and find the greatest number.

These kinds of row-wise comparisons cut out a lot of writing OR clauses. Though standard function rules apply: if you put these in the WHERE clause of queries against large tables and expect them to be your primary filters and you’ll probably be in for a nasty surprise.

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Chad Baldwin checks out what’s new:

I’ve been exicted to play around with some of the new features and language enhancements that are available in SQL Server 2022 so I’ve been keeping an eye on the Microsoft Docker repository for a new 2022 image. Well, they finally added it to Docker Hub! I immediately pulled the image and started playing with it.

I want to focus on the language enhancements as those are the easiest to demonstrate, and I feel that’s what you’ll be able to take advantage of the quickest after upgrading.

Read on for a dozen or so language enhancements. This isn’t as big a change as what 2012 brought but there is a lot of useful stuff in here, as well as more that has been publicly announced like APPROX_PERCENTILE_CONT() (and _DISC(), yeah, but bah humbug).

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Itzik Ben-Gan knows how to inspire joy:

Microsoft recently released the first public preview of SQL Server 2022. This release has a number of T-SQL improvements. In this article I focus on windowing and NULL-related improvements. These include the new WINDOW clause and the windowing NULL treatment clause.

I’ll be using the sample database TSQLV6 in the examples in this article. You can download this sample database here.

I’ve been waiting for INGORE NULLS since they previewed it in Azure SQL Edge.

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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.

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