New Features for Administrators - Question 029

Examine this statement, which creates a Cartesian product of the COUNTRIES and REGION tables:

SQL> SELECT c.country_name,
2> r.region name
3> FROM countries c, region r;

Oracle9i SQL: 1999 syntax supports the same functionality with which join type?

A. Equijoin

B. Cross join

C. Merge join

D. Natural join

Answer: B

Explanation:

The CROSS JOIN operation creates a Cartesian product of two tables. It’s the same operation performed when you specify two or more comma-separated tables in the FROM clause without specifying a join condition.

Incorrect Answers

A: The EQUIJOIN operation requires usage of equity operation.

C: The MERGE JOIN operation is used to either update existing rows or insert new rows into a destination table. You update the row in the destination table if there is a matching row in the destination table; otherwise, you insert a new row into the destination table.

D: The NATURAL JOIN matches rows that have equal values in all columns that have the same name.

OCP Oracle9i Database: New Features for Administrators, Daniel Benjamin, p. 242-249

Chapter 5: Language Enhancements

Oracle 9i New Features, Robert Freeman, p. 158-161

Chapter 6: Oracle9i SQL, PL/SQL New Features