Few subjects provoke as much passion as the question of how to capitalize programming code.
You've got C-like languages where case is significant, but the discussion continues whether to string_words_along or JamWordsTogether. My own convention for PL/SQL is a bit idiosyncratic. I decide whether a particular subprogram is more procedural or more object-oriented, and use underscores or Camel case as appropriate for each one.
Then you've got lots of other languages, like PL/SQL, where case is not significant. But you'd still like to format source code for readability and comprehensibility. I commonly see the convention of reserved words in all caps, and lowercase for names of tables, variables, etc. That allows for some degree of consistency in documentation -- you can talk about "the IF statement" and the reserved word is easy to pick out even if the text is stripped of all formatting in a man page or an e-mail. But if Oracle ships packages like DBMS_OUTPUT, does it make sense to capitalize those names as if they're reserved, or treat them more like user-defined objects? Rather than drive myself to distraction, I use lowercase for everything in source code (after all, nobody ever accused C or Perl code of being hard to read... er... :-). When referring to reserved words in text, I use all-caps.
Now, I am well aware that there is an uppercase stigma attached to some languages. FORTRAN 77 was case-sensitive and got endless grief for that. (Why, I left my small-town roots rather than accept a job working in FORTRAN.) Fortran 90 enabled the use of lowercase, which was such a big deal that it was reflected in the language name. At IBM, where I eventually worked my way up to working on XL Fortran :-), it was common to switch within the same sentence: "The IBM Toronto Lab took over the FORTRAN mission, and released several Fortran compilers, while the mainframe FORTRAN products continued to be developed by the Santa Teresa lab". This after years of working on Ada, which also had an uppercase stigma because everyone assumes it should be ADA. (It's Ada, because it's an eponym not an acronym.)
There is some uppercase lurking inside the database. Issue create table foo and it will dutifully create a table named FOO, as you can see by 'select table_name from user_tables'. You can make the table be named FooBar by enclosing the name in double quotes: create table "FooBar". But then you have to put the quotes everywhere you refer to the table, so it's not worth the trouble except in unusual circumstances where you want to obscure the name, or have names identical except for case.
The tilt towards uppercase means you more often see code like this for doing case-insensitive matches:
select last_name from my_table where upper(last_name) like 'A%';
You could just as well write:
...lower(last_name) like 'a%';
and people might regard that line with more respect. These days, out of principle, I always use a regular expression instead:
select last_name from my_table where regexp_like(last_name,'^a','i');
In real code, anyway. On the command line, I still slip back into LIKE out of habit. It puzzles me a bit that SQL can't handle the BOOL... bool... Boolean datatype of PL/SQL, yet regexp_like is testing a Boolean condition without any comparison operator.