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Project

  • Output relation contains all rows, but only the specified columns.
  • Duplicates are eliminated, because relations are sets.


R

X Y Z
1eee10
1eee20
2eee30
2fff40
3fff50
4fff60
4fff70


project(R, [X, Y])

X Y
1eee
2eee
2fff
3fff
4fff

  • In the projected rows, there are duplicates:
    • (1, eee) occurs twice.
    • (4, fff) occurs twice.
  • There is one occurrence of each in the result.

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