What good reasons are there to capitalise SQL keywords?

Question

There seem to be a lot of developers who write their SQL by capitalising the keywords:

SELECT column
FROM table
     INNER JOIN table
     ON condition
WHERE condition
GROUP BY clause
HAVING condition

I'm wondering why people stick to this approach? Clearly, it's a long established convention - but I've never run into a RDBMS that requires capitalisation.

Personally, I find KEYWORDS THAT SHOUT to be calling attention to exactly the wrong part of the query, which is why I write the keywords in lowercase.

Still, enough people use this convention that I figure I might be missing something, hence this question.

Answer 1

Capitalization makes them stand out, as opposed to the other characters that are in the query window.

The reason I don't do this as it's a huge time waster. You can do one of two things:

1) Hold your shift key down while typing out the word: way too error-prone and just haphazard.

2) Put on caps lock for the duration of the word: a bit too much of time consumption.

I use SQL Server, and the environment (SSMS) has great syntax highlighting so I don't personally believe keyword capitalization is as prevalent these days as it used to be (if at all).

It is good practice in books and online tutorials, though, so it is evident what the reserved keywords are. It's just one of those unwritten things.

Answer 2

I find this sort of capitalization provides a quick and easy way to visually break up the different parts of the query. This combined with good indentation can help the readability and understanding of the logic.

Whether or not that has anything to with how the standard came about, I don't know. But that's my personal experience.

Answer 3

Well back in the olden days, keywords weren't highlighted in any way when you wrote code so it was an attempt to help people differentiate between the SQL parts and the database objects parts of the queries, it could have gone the other way but objects tend to have longer names making them more of a pain to capitalize and some object naming conventions were case specific.

Personally I find it just as easy to read if they aren't capitalized but many people are so used to reading them that way, it throws them off if you don't capitalize.

Answer 4

SQL is a clause-oriented language, much more than anything else I've experienced. You've got your SELECT clause, and your FROM clause, and your JOIN clause(s) and your WHERE clause. ORDER BY, GROUP BY, etc, etc.

Capitalizing those keywords helps you visually separate the separate clauses. This is especially handy when in one of those tricky debugging situations where you're outputting your SQL in an HTML comment, then copy-pasting into a console. Nasty, but we've all been there. It's good to have some help seeing where each piece of the statement starts.

Answer 5

Personally, I find KEYWORDS THAT SHOUT to be calling attention to exactly the wrong part of the query, which is why I write the keywords in lowercase.

As has been pointed out, with old IDE's you didn't have many options besides casing to differentiate text. As you point out, making the keywords stand out draws your attention away from where it should be. The issue is that you know keywords can always be capitalized, whereas the other stuff can contain literals and identifiers that are case sensitive. This lead to the path of least resistance being to just capitalize the keywords.

Answer 6

In my case, I prefer to capitalize the keywords, independently of syntax highlighting. Imagine that you don't have a proper SQL editor and you need to write/edit or open your scripts in Notepad or WordPad. These editors doesn't have a syntax highlighting.

I don't pay much atention to the syntax highlighting of SQL Server for the same reason that I described above, but it's useful (it's bored for me to see all the code in black). I have always used uppercase to distinguish keywords from my variables, constants, names, etcetera.