Rename (relational algebra)

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

  • is a relation
  • and are attribute names
  • is an attribute of

The result is identical to except that the attribute in all tuples is renamed to . For an example, consider the following invocation of on an 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 with the attribute renamed to so that: