Notepad++ is a text editor, so you can now use it to edit your SQL file. After selecting the Language > SQL, Notepad++ will highlight SQL syntax as you type. Try typing some SQL, like
SELECT "Hi";
SELECT * FROM mydatabase WHERE id LIKE 'ID%';
You will see color, bold, and other possible formatting applied to the text you type. If you save the file as something.sql, and then load something.sql in your SQL client, the client will run the SQL commands from that file. If you have an existing somethingElse.sql file, you can open it in Notepad++, which will auto-recognize that it’s SQL and apply the syntax highlighting, allowing you to edit it and save it.
By using the Run > Run dialog, you can run an arbitrary command. For example, if your SQL client has a command-line mode accessed thru sqlclient.exe, you could type
c:\path\to\sqlclient.exe $(FILE_NAME)
If you just run it, that probably won’t show you any results… but if you ran
cmd /k c:\path\to\sqlclient.exe $(FILE_NAME)
It will open a new cmd.exe Windows command prompt, and show the output from that file.
If instead of running, you hit “SAVE”, you can give it a name (which will end up later in the Run menu), and/or a keyboard shortcut, so that you can easily re-use that many times.
If you want to do something more fancy, use the NppExec plugin, which includes a better batch/scripting language. Once again, you can save the NppExec script, and make it show up in the Macro menu.
If Python is a programming language you know or could learn (or if, like me, you know enough other programming languages that you can fake the Python), then the Python Script plugin will allow you to do even fancier stuff. (Python is a complete programming language, and has many libraries written, which could act as an interface between your SQL source file and your database engine; PythonScript has access to a full python2.7 interpreter. For example, you could write a script in Python which executes the commands from your SQL, grabs the results from your database engine, and displays them in Notepad++, either inline with your original SQL code, or in a new text document. You are really limited only by your imagination and knowledge of Python.)