Abstract: A method for emulating an Object-Oriented database (OODB) on a Relational database, comprising: define the desired data structure as objects for an Object-Oriented database; for each object, open an RDB table; for each object, in the RDB table, define relevant fields; implement an OODB interface with the user while storing the information in RDB tables. A method for emulating an Object-Oriented database (OODB) on a Relational database and for distinguishing between OODB objects, comprising: define the desired data structure as objects for an Object-Oriented database: for each object, open an RDB table: for each object, in the RDB table, define relevant fields; allocate a unique primary number object-id to each new object; allocate a second number to each new object, wherein its value is computed as the product of its object-id and its parent's object-id; implement a method to support the application of SELECT commands over the tables using the object-id and item-id numbers, to return the relevant objects.