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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-product (Cartesian operator)?
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Yes, you can! The longer answer is yes, there are a few ways to combine two tables without a common column, including CROSS JOIN (Cartesian product) and UNION. The latter is technically not a join but can be handy for merging tables in SQL. In this article, I'll guide you through the different solutions with examples.
The common complaint about NATURAL JOIN is that since shared columns aren't explicit, after a schema change inappropriate column pairing may occur. And that may be the case in a particular development environment.
Method 1 (Cross Join): As you might have heard of several joins like inner join, outer join, in the same way cross join is there, which is used to form the Cartesian product of the tables without or with common columns.
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.
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A cartesian product of two tables will be returned.This is because when we perform any JOIN operation on two tables a cartesian product of those tables is performed and then based on any select condition in WHERE clause the resultant rows are returned.But here as there are no common columns the process stops after cartesian product.
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