1. A computer program product embedded in a non-transitory computer readable medium for implementing a temporal relational database, the computer program product comprising: computer code for creating a temporal history for every transaction entered into a relational database using a value time history and a schema time history, the value time history having an entry for each transaction that causes an value change in an attribute of a data model represented by one or more tables of the relational database that indicates a valid time having no upper bound during which the value change is valid, the scheme time history having an entry for each transaction that causes a schema change in the data model represented by the one or more tables of the relational database that indicates a valid time having no upper bound during which the schema change is valid; and computer code for ensuring that the temporal history created for every transaction entered into the relational database conforms to a temporal relational database model, wherein the computer code for ensuring that the temporal history created for every transaction entered into the relational database conforms to the temporal relational database model includes: computer code for receiving a transaction that causes a value change in an attribute of the data model represented by the one or more tables of the relational database, computer code for determining a valid time for the transaction during which the value change is valid, computer code for enforcing a condition upon the valid time for the transaction during which the value change is valid requiring the valid time to be simultaneously valid in accordance with an intersection between the determined valid time for the transaction and the valid time of an entry in the schema time history during which the attribute of the data model represented by the one or more tables of the relational database is valid and whose value changes based on the transaction, and storing an entry for the transaction in the value time history that includes a valid time during which the value change is valid that satisfies the condition.