Someone got hired as an IT Support Desk Technician. On his 5th day, he told the CEO that this job was temporary and he had no intentions of staying as he wanted to work in IT in a school.
Dont tell your boss you dont expect to be there long.
Dont expect your workers to want to be there long unless you offer good options to advance and educate themselves. Especially for a help desk job... that's very often an entry job to get a foot into the IT door.