• I have shrunk TempDB by selecting it under Object Explorer, right-clicking on it, and choosing the relevant sub-menu option (SQL 2012 Express) that appears. It worked a treat, as I was able to shrink it back to whatever I wanted to. (Apologies, I'm not on the machine with SQL installed so I cannot remember the exact sub-menu option). My file expanded as I executed some poorly-construed SQL, so I was clearing up my own mistakes.