Full width home advertisement

How To

Science

Post Page Advertisement [Top]


What is Join in DBMS?

Join is a collection of a Cartesian product followed by a selection process. A Join operation matches two tuples from different relations, if and only if a given join term is fulfilled.

What is Theta (θ) Join in DBMS?

Theta join merges tuples from different relations provided they meet the theta condition. The join condition is represented by the symbol θ. Theta join makes use of all types of comparison operators.

What is Equijoin in DBMS?

Equijoin is defined as when Theta join make uses of only equality comparison operator.

What is Natural Join () in DBMS?

Natural join operates on those corresponding attributes where the values of attributes in both the relations are similar. Natural join doesn’t combine or merge the manner a Cartesian product does. 

What are Inner Joins in DBMS?

Inner joins consists of only those tuples with corresponding attributes and the rest are discarded in the resulting relation. Inner Join consist of Theta Join, Equijoin, and Natural Join.

What are Outer Joins in DBMS?

Outer Joins consists of all the tuples from the participating relations in the resulting relation. There are three main types of outer joins:

Right Outer Join: All the tuples from the Right relation, S, are comprised in the resulting relation. If there are tuples in S without any corresponding tuple in R, then the R-attributes of resulting relation are made NULL.

Left Outer Join: All the tuples from the Left relation, R, are added in the resulting relation. If there are tuples in R without any corresponding tuple in the Right relation S, then the S-attributes of the resulting relation are made NULL.


Full Outer Join: All the tuples from both participating relations are added in the resulting relation. If there are no corresponding tuples for both relations, their respective matchless attributes are made NULL.

No comments:

Post a Comment

Bottom Ad [Post Page]

| Designed by Colorlib