For me SQL has long been the gateway to the world of development. I work in the UK non-profit sector and traditionally this kind of technical knowledge is rare, so for any team I've worked with I've built learning pathways that start with SQL before pushing out into Python, Linux, and other things. We're not exactly at the bleeding edge of current technologies, but SQL has consistently proved to be a great jumping-off point for novices who have even a passing interest in computing.