Is there a SQL journal for publishing developments in the program?

There are a lot of trade magazine and user groups. For example, The Processional Association for SQL Server (PASS), which serves the Microsoft SQL Server community, is huge. and SQL Server Pro magazine/website.

I’m familiar with those, I am sure there equivalents for the other particular SQLs like Oracle and MySQL.

I think journals would be higher up the food chain, for people in computer science who conceive things like SQL. We users are just trying to be as clever as possible with features which were built into the software.

But back to your idea – I learn a huge amount from the sources I list above, and much of it comes from people like yourself who are generous enough to share their ideas.

What have you cooked up?
“done something in SQL” is a bit vague. Are you sure it’s novel or is it something you hadn’t seen in your environment before ?

There are journals out there but most of them are about seriously fundamental advances in relational database theory.

SQL is not a program. It’s a query language (Structured Query Language, to be precise.)
SQL is an open specification that a lot of different programs use. I can’t tell from your question which program you are using that implements SQL. Your development is probably most useful in the context of that particular program or system.

SQL is also a standard published by ISO/IEC. If you think your development is possibly beneficial to the SQL standard, then you could attempt to contact the relevant part of that standards organization. I have no idea how to do this. Maybe this will help:
http://www.iso.org/iso/home/standards_development.htm

Its a stored function that allows reporting of medians and quartiles easily even when grouping. All the recomendations I’ve seen involve sorting and taking the middle of the list which is tedious if you have to limit to various groups one at a time or look at multiple columns.

That’s good, and there are several mailing lists (for example) where you can share this information.
I can’t recommend or research a particular one, since I don’t know which database program or which implementation of SQL you are using. MSSQL in Microsoft SQL Server is different from MySQL, which is different from PostGreSQL, and so on.

if it would be published in a SQL journal that would be able to go on my curriculum vitae.