Oracle Database SQL — Question 179

Which two are true about self joins? (Choose two.)

Answer options

• A. They can use INNER JOIN and LEFT JOIN.
• B. They require the EXISTS operator in the join condition.
• C. They require the NOT EXISTS operator in the join condition.
• D. They require table aliases.
• E. They have no join condition.
• F. They are always equijoins.

Correct answer: A, D

Explanation

The correct answers are A and D because self joins can indeed use INNER JOIN and LEFT JOIN as well as require table aliases to differentiate the instances of the same table. Options B, C, E, and F are incorrect as self joins do not inherently require EXISTS or NOT EXISTS operators, do have join conditions, and are not always equijoins.