Oracle SQL Oracle SQL Joins and Subqueries

Question 1

Which type of JOIN returns only rows where there is a match in BOTH tables?

Accepted Answer

INNER JOIN

Answer

LEFT OUTER JOIN

Answer

FULL OUTER JOIN

Answer

CROSS JOIN

Question 2

What does a LEFT OUTER JOIN return in Oracle SQL?

Accepted Answer

All rows from the left table and matching rows from the right

Answer

Only rows matching in both tables

Answer

All rows from the right table and matching rows from the left

Answer

All rows from both tables regardless of match

Question 3

In Oracle SQL, what is the legacy syntax equivalent of a LEFT OUTER JOIN?

Accepted Answer

table1, table2 WHERE table1.id = table2.id(+)

Answer

table1, table2 WHERE table1.id(+) = table2.id

Answer

table1 LEFT JOIN table2 USING (id)

Answer

table1, table2 WHERE table1.id *= table2.id

Question 4

What does a CROSS JOIN produce in Oracle SQL?

Accepted Answer

A Cartesian product of all rows from both tables

Answer

Only matching rows from both tables

Answer

Rows that exist in one table but not the other

Answer

NULL rows for non-matching records

Question 5

Which Oracle SQL subquery type returns a single value used in a WHERE clause comparison?

Accepted Answer

Scalar subquery

Answer

Correlated subquery

Answer

Inline view

Answer

Exists subquery

Question 6

What is a self-join in Oracle SQL?

Accepted Answer

Joining a table to itself using aliases

Answer

Joining two copies of different tables

Answer

A join that uses no WHERE condition

Answer

A join between primary and foreign key columns only