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Relational Algebra Operations (cont)

Projection
  • πX(r)   =   Proj[X](r)   =   { t[X]  |  t ∈ r }
  • X ⊆ R ;  result schema is given by attributes in X
Computational view: 

result = {}
for each tuple t in relation r
    result = result ∪ {t[X]}