Wednesday, 6 August 2014

Relational Query Languages |RELATIONAL COMPLETENESS


RELATIONAL COMPLETENESS

The notion of relational completeness was propounded by codel in 1972 as a basis for evaluating the power of different query language.A language is relation-ally complete if the basic relational algebra operation can be performed.The basic relational algebra operations are-
  • UNION
  • CROSS PRODUCT
  • SELECTION
  • DIFFERENCE
  • PROJECTION
Query language that are actually used in practice provides features in addition to one mentioned above.

FOR EXAMPLE-They provides the facilities for-
  • Modification,storage and deletion information
  • Printing relation
  • Assigning relation to some relation name
  • Computing aggregate function like Sum and Max
  • Performing Arithmetic operation

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