NoSQL databases are quite the rage these days (e.g. MongoDB) employing JSON based data. JSON lends itself well to document based databases, and the JAVA List and Map constructs can easily be used with JSON to describe almost any type of data your application uses. In those cases requiring large scale databases and your data is object oriented (or document based), the new NoSQL databases will work nicely for you.

However, if all you need is to keep your database mostly in memory, there really isn't a way to easily query your data without writing a lot of custom code. This is where JSON Query Language can work for you. By storing your objects in a JQL database, you can use familiar SQL commands to query your data. There is no need to create your own query mechanisms or object store. JQL will handle all of that for you. The database can be stored and retrieved from disk, and uses the familiar JSON format to store your data.

However JQL supports the standard SQL commands such as "Select", "Insert", "Update", "Delete", and "Drop" can be used to accomplish almost everything that one needs to do with a relational database. Because JQL databases are object oriented, SQL was modified slightly to accommodate the document within document (object within object) data structure so that inner objects can be queried easily.

Like other NoSQL databases, JQL does not support the concept of a JOIN. Instead embed the data you would expect on a JOIN, even if this results in duplicate data. The cost of memory is low, and the removal of the necessity of the JOIN greatly increases the speed of operations.

Diections on how to build, use and extend JQL is doumented in Users Guide.odt (or Users Guide.pdf.