Rename (relational algebra)

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In relational algebra, a rename is a unary operation written as where:

The result is identical to R except that the b attribute in all tuples is renamed to a. For an example, consider the following invocation of ρ on an Employee relation and the result of that invocation:

Name EmployeeId
Harry 3415
Sally 2241
EmployeeName EmployeeId
Harry 3415
Sally 2241

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: