Join Operators in DBMS

Cartesian product returns all the possible associations among the relations. Out of these only a subset of rows would be returned by the join operators.

Join operators can be divided in two such categories:

  1. Join Type
  2. Conditions
Types Conditions
Inner Natural (Equi Join)
Left Outer ON Condition
Right Outer Using Attributes
Full Outer or Outer

Join Types:

Signifies the following points

  • The decision on the types of rows returned that is matched or un-matched rows.
  • The procedure of placing the matched rows in the result based on the requirements.

Join Conditions:

Signifies the following points

  • The predicate that shall get applied while joining the tables. The predicate shall get used in evaluating whether a row is matched or not.
  • Join condition also signify list of columns that are allowed in the result set.

Join Types in detail

Join condition in detail

 

 

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