I have to disagree that 4GL languages being aimed at the big iron, mainframe world. After browsing the Wikipedia page, there seems to be some confusion around what a 4GL would actually be... For instance, RPG is lumped into this category despite it functioning at a pretty low level and predating the idea by about 30 years. When I first started working with RPG we had worksheets from IBM that felt reminiscent of punch cards.

In my experience, most 4GL languages were aimed at microcomputers and did reasonably well. Others have mention FoxPro and dBase, 4D and FileMaker also slot nicely into this category. IMHO, they had great success in the back office of small businesses.

I have seen some effort to force SQL into this category, perhaps with the idea that a SQL database with stored procedures technically meets the 4GL definition.