In relational algebra, a rename is a unary operation written as
ρ
where: The result is identical to R except that the b attribute in all tuples is renamed to a.
[1] For an example, consider the following invocation of ρ on an Employee relation and the result of that invocation: Formally, the semantics of the rename operator is defined as follows: where
is defined as the tuple t, with the b attribute renamed to a, so that: