Category: T-SQL

Chris Johnson finds a language quirk:

Recently I found a quirk of T-SQL, where a group by statement was treating strings as the same if the only difference was one or more trailing spaces. So, ‘aa’ would be grouped with ‘aa ‘. I did some digging, and this is what I found.

Yeah, this isn’t just Microsoft’s T-SQL variant—it’s a standard part of SQL, as Chris notes later in the post.

My “just-so” story is that this might have been implemented to deal with CHAR(x) comparisons, such as CHAR(2) to CHAR(3). There’s no way to make that comparison unless you treat trailing spaces as irrelevant. Because we almost always use VARCHAR(x) or NVARCHAR(x), it isn’t something top of mind to most database practitioners, but there is a method to the madness.

Kevin Wilkie doesn’t like misshapen XML data:

Sometimes you’ll find that you will have XML in your database. This could be for various reasons – from storing the XML after receiving an API response to keeping it in a table because a web developer couldn’t figure out another way to store their data. Sometimes – no matter how much you trust your source – you should question if the XML is well-formed. Let’s work out a few ways you can do that in a database.

Read on for a few tests. The more concerned you are about XML data quality, the more you’d want to push in the direction of having an XSLT defined as well.

Bob Pusateri keeps it all straight in his head:

Ooh! A mnemonic! And a pretty good one at that. The idea being that the first letter of each word of the sentence helps you remember something else, like the order of the major parts of a SELECT statement:

SELECT
FROM
WHERE
GROUP BY
HAVING
ORDER BY

Click through for Bob’s best attempts. Oddly enough, now I want some Rally’s fries. Or maybe Checkers—I can’t decide.

Aaron Bertrand gives it a go:

A while back, I wrote a couple of tips about simulating TRY_CONVERT – a function added in SQL Server 2012 – in earlier versions (see Part 1 and Part 2). Recently, someone in the community had a similar requirement: they wanted to make TRY_PARSE work for dates in SQL Server 2008. Now, I’m not one to help people stay on versions of SQL Server that are now 15 years old, but I do acknowledge that hands may be tied, and they can’t always control the version they’re stuck with.

Aaron does this community member a solid, though it’s probably something you’d never want to use if you’re on SQL Server 2012 or later.