A set of basic collection-like operations backed by an SQL database is available in [ANN] SQLStore.jl: use SQL tables as persistent Julia collections.
It presents tables with interface similar to arrays or dicts, see the notebook for some examples. Stuff like push!, filter, count, etc.
SQLStore is not a full Julia-SQL translation layer, so not exactly what you are looking for. Still, it is helpful for eg loading the required subset of the whole SQL table into memory. After that, just use familiar Julia in-memory tools (: