Relational Algebra

  • Relational Algebra is a procedural query language - what operation and how to do on database is told.
  • It consists of set of operations that take one or two relations and produces another relation as output is another relation
  • Input relations remain intact
  • Output of one relational operation can become input of another operation and this can be done iteratively
  • Relational expressions can be nested just as in arithmetic 
  • Most of the data retrieval operations can be done using 5 basic operations:-
  • Selection
  • Projection
  • Union
  • Cartesian Product
  • Set Difference
  • Other operations required can be expressed in terms of basic operations:-
  • Join
  • Intersection
  • Division