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relational-databasecartesian-productrelational-algebracross-joinnatural-join
Hate
Hate

Reputation: 1235

Natural join if no common attributes

What will natural join return in relational algebra if tables don't have attributes with same names? Will it be null or the same as cross join (cross product) (Cartesian product)?

Upvotes: 24

Views: 26127

Answers (3)

Prashant_M
Prashant_M

Reputation: 3134

The cartesian product of the two tables will be returned. This is because, when we perform any JOIN operation on two tables, a cartesian product of those tables is formed. Then, based on any select condition in the WHERE clause, the resultant rows are returned. But here, as there are no common columns, the process stops after finding the cartesian product.

Upvotes: 9

ruqaiya
ruqaiya

Reputation: 1

It will return the cartesian product of the tables. If there are any common attributes, then the natural join removes the duplicate attributes.

Upvotes: -1

Andrew Martin
Andrew Martin

Reputation: 5741

If there are no attributes in common between two relations and you perform a natural join, it will return the cartesian product of the two relations.

Upvotes: 32

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