Oracle SQL Oracle SQL Joins and Subqueries 2

Question 1

Which Oracle SQL operator checks if a subquery returns at least one row?

Accepted Answer

EXISTS

Answer

EXISTS returns TRUE if the subquery produces at least one row, and is often more efficient than IN for large datasets.

Question 2

What is an inline view in Oracle SQL?

Accepted Answer

A subquery used in the FROM clause

Answer

An inline view is a subquery placed in the FROM clause, treated like a temporary table within the query.

Question 3

What does a correlated subquery do in Oracle SQL?

Accepted Answer

References a column from the outer query and executes once per outer row

Answer

A correlated subquery references columns from the outer query and is re-executed for each row processed by the outer query.

Question 4

Which keyword allows you to join tables using a column with the same name in both tables in Oracle SQL?

Accepted Answer

USING

Answer

The USING clause joins tables on a column that has the same name in both tables, and the column is not qualified with a table prefix in the result.

Question 5

What does the NATURAL JOIN keyword do in Oracle SQL?

Accepted Answer

Joins tables based on all columns with the same name

Answer

NATURAL JOIN automatically joins tables on all columns that share the same name and data type in both tables.

Oracle SQL Practice Test