Xbase DBMS is a C++ library which supports access to Xbase type datafiles and indexes (ie., .dbf and related files). It provides access at the record level to these files.
XBSQL is a wrapper library which provides an SQL-subset interface to Xbase DBMS. XBSQL by no way provides anything like a complete SQL implementation, and in any case is hampered by various limitations of XBase (such as no notion of a null value). However, it implements a fairly useful subset, including select, insert, update and delete; select for instance supports joins, ordering, grouping and the having clause.
The remainder of this document is a brief programming manual for the library. You may with to refer to the xql.cpp, the source of a minimal command-line client.