In relational algebra, a rename is a unary operation written as
\rhoa/b(R)
The result is identical to except that the attribute in all tuples is renamed to .[1] For an example, consider the following invocation of on an relation and the result of that invocation:
- ! Employee | \rhoEmployeeName/Name(Employee) | - style="vertical-align: top" |
---|
Formally, the semantics of the rename operator is defined as follows:
\rhoa/b(R)=\{ t[a/b]:t\inR \},
where
t[a/b]
t[a/b]=\{ (c,v) | (c,v)\int, c\neb \}\cup\{ (a, t(b)) \}.