Relational Algebra - Division Operator

About

The division relational operator permits to find values in an attribute of R that have all values of S in the attribute of the same name

There is no SQL equivalent.

Symbol

<MATH> \LARGE R \div S \\ or\\ \LARGE R / S </MATH>

Formula

The division of R by S that return all values of the attributes R.t that have a row with all value in S.s can be expressed as: <MATH> \LARGE R / S \equiv \{\; \left<\vec t\right> \;|\; \forall \left<\vec s\right> \in S, \left< \vec t \vec s \right> \in R \;\} </MATH> where:

  • <math>\forall</math> means for all
  • <math>\vec t \vec s</math> are vector

Example

Documentation / Reference


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