Single file PHP script that adds a REST API to a MySQL InnoDB database. Alternatively SQLite 3, PostgreSQL 9 and MS SQL Server 2012 are fully supported.

Limitations

Authentication is not included
Composite primary or foreign keys are not supported
Complex filters (with both "and" & "or") are not supported
Complex writes (transactions) are not supported
Complex queries calling functions (like "concat" or "sum") are not supported
Batch operations for insert, update and delete are not supported