What is object identity in Advance DBMS?

An object retains its identity even if some or all the values of variables or definitions of methods change over time. This concept of identity does not apply to tuples of a relational database. In relational systems, the tuples of a relation are distinguished only by the values that they contain. It is a conceptual notion; actual system requires a physical mechanism to identify objects uniquely.

The types of object identity are given below-

a. Value: A data value is used for identity. This form of identity is used in relational systems. For instance, the primary key value of tuple identifies the tuple.

b. Name: A user-supplied name is used for identity. This form of identity typically is used for files in file systems. Each file is given a name that uniquely identifies the file, regardless of the contents of the file.

Built-in: A notion of identity is built into the data model or programming language and no user-supplied identifier is required. This form of identity is used in object-oriented systems. Each object is automatically given an identifier by the systems. Each object is automatically given an identifier by the system when that object is created.