Keeps only a subset of attributes.
project(operand: Relation, attributes: AttrList) -> Relation
project(suppliers, [:city], allbut: true)
Computes the relation obtained by projecting tuples from
operand on a
subset of their attributes.
This operator supports an ALL BUT variant, through the
When set to true, the operator removes specified attributes instead of
keeping them. An
allbut operator is also provided that has the same
Unlike SQL, this operator ALWAYS remove duplicates. There is no way, in Alf, to compute bags of tuples.