In the beginning apps and SQL were co-mingled. Oracle eventually came along and noticed that people wanted SQL on the network so that many different apps, running on different computers, could all access the same data. But then people realized that clients really want rich, 'tree'-like data, not simple rows and columns, so people started sticking networked databases in front of networked databases to serve as a transformation system. And now people are realizing that the second networked database layer is redundant and never used beyond what is required for the client-facing network database, so they are moving the storage back into the first network database layer, just like Oracle did all those years ago. What is old is new again.