Which statement describes a natural join?

Which statement describes a natural join?

• A. It requires a join predicate to be specified in an ON clause.
• B. It returns the Cartesian product of the two tables.
• C. It automatically matches on all columns with the same names and removes duplicate columns.
• D. It cannot be used with multiple tables.

Answer: (C)

Natural join automatically uses all columns that have the same name in both tables as the join condition, performing equality comparisons on those common columns and returning only one copy of each shared column. Because the join condition is implicit, you don’t specify an ON clause. This is different from the Cartesian product, which would pair every row from one table with every row from the other. You can apply natural joins across more than two tables by chaining them, so the concept isn’t limited to just two tables.

Natural join automatically uses all columns that have the same name in both tables as the join condition, performing equality comparisons on those common columns and returning only one copy of each shared column. Because the join condition is implicit, you don’t specify an ON clause. This is different from the Cartesian product, which would pair every row from one table with every row from the other. You can apply natural joins across more than two tables by chaining them, so the concept isn’t limited to just two tables.