In this case SSN is said to be a determinant since it determines the value of another attribute. The relationship between SSN and Name is said to be a functional dependency . Constraints on domains may not be time-dependent. The Database in Action Application programs are created to provide a user interface to manipulate the database in ways that the database management system may not directly support. Application programs may be written in an ordinary general purpose programming language, a language specific to the particular DBMS or a standard language such as SQL that is designed to manipulate databases.
Transactions are representations of events.
These events are normally the interaction between entities in the database. File sharing must occur when two or more users must be given simultaneous access t the same entity at the same time. A Logical Key is a collection of one of more attributes of a relation that form a unique identifier. A Physical Key is a collection of one or more attributes defined as such to the DBMS which then builds a key structure to facilitate fast access to records containing a specified key value. Physical keys need not be unique identifiers although most commonly they are.