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NIELIT 2017 OCT Scientific Assistant A (IT) - Section B: 27

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Ans: D) All of the above

 

  • We can not do Aggregate computation(sum, avg, etc) and multiplication with relation algebra.
  • Although relational algebra seems powerful enough for most practical purposes, there are some simple and natural operators on relations that cannot be expressed by relational algebra. One of them is the transitive closure of a binary relation. Given a domain D, let binary relation R be a subset of D×D. The transitive closure R+ of R is the smallest subset of D×D that contains R and satisfies the following condition:

          There is no relational algebra expression E(R) taking R as a variable argument that produces R+

 

References: https://en.wikipedia.org/wiki/Relational_algebra

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ans : D desired features are beyond the capability of relational algebra

 

  1. Aggregate Computation
  2. Multiplication
  3. Finding transitive closure
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