Subset of SQL for specifying non-procedural queries for Java objects
EditBy: Subset of SQL for specifying non-procedural queries for Java objects, index access based on T-Tree, parallel excecution of requests
JSQL is subset of SQL languages, which can be used to select objects instances according to selection condition. JSQL can be used for implementing personal minidatabase, as tool for dynamic compilation and Execution of user requests. JSQL uses notation more popular for object-oriented programming then for relational database. Table rows are considered as object instances and the table - as class of these objects. Unlike SQL, JSQL is oriented on work with objects instead of SQL tuples. So the result of each query execution is a set of objects of one class. The main differences of JSQL from standard SQL are:

There are no joins of several tables and nested subqueries. Query always returns set of objects from one table.
Standard C types are used for Atomic table columns.
There are no NULL values, except null references. I am completely agree with C.J. Date critics of three-value Logic and his proposal to use Default values instead.
Arrays can be used as record components. Special exists quantor is provided for locating element in arrays.
User methods can be defined for table records (objects) as well as for record components.
References Between objects are supported including automatic support of inverse references.
As far as query language is deeply integrated with Java language, case sensitive mode is used for language identifiers as well as for keywords.
No implicit conversion of integer and floating types is done to string representation. If such conversion is need, it should be done explicitly. you can free download Java embedded SQL(unix) 1.08 now.