1. A method of operating a computer system to create a relational database schema from a semantic object model, comprising the steps of: creating, in response to a user input, one or more semantic objects each of which represents an item about which data is stored in one or more tables of a relational database; creating, in response to a user input, one or more attributes and associating the attributes with one or more semantic objects, each of the attributes representing data stored in the relational database for the item represented by the semantic object with which the attribute is associated, the attributes including simple value attributes that represent the data entry in a single column of the relational database, group attributes having one or more member attributes that represent a logical collection of attributes and object link attributes that represent relationships between the semantic objects in the semantic object mode each of the attributes having one or more properties and wherein each attribute is associated with a corresponding simple value, group or object link profile that defines default values for the one or more properties of the associated attribute; storing in the computer system an indication for each attribute whether the attribute is multivalued, thereby representing multiple data entries in a column of a relational database; translating the semantic objects and their associated attributes into the one or more relational database tables, by operating the computer system to perform the steps of: automatically generating a relational database table for each semantic object in the semantic object mode; automatically analyzing each attribute associated with a semantic object to determine whether the semantic object is associated with a multivalued group attribute having a multivalued attribute as a member attribute, and if so: a) creating a second relational database table for the multivalued group attribute and linking the second relational database table to the relational database table created for the semantic object by a foreign key; and b) creating a third relational database table for the multivalued attribute that is a member attribute of the multivalued group attribute and linking the third relational database table to the second relational database table by another foreign key.