Oracle Database SQL Certified Associate Exam Practice Test

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The Oracle Database SQL Certified Associate certification is a testament to your understanding and proficiency in SQL, data modeling, and using SQL to create and manipulate tables in an Oracle Database. To help you prepare for this prestigious certification, we’ve created a practice test consisting of 25 multiple-choice questions, each accompanied by the correct answer and a detailed explanation.

1. Which SQL clause is used to provide a summary value, like a sum or average?

A) SELECT
B) ORDER BY
C) GROUP BY
D) JOIN

Answer:

C) GROUP BY

Explanation:

The GROUP BY clause groups rows that have the same values in specified columns into summary rows, like finding the sum or average.

2. Which SQL keyword is used to prevent duplicate records from appearing in a query result?

A) DISTINCT
B) UNIQUE
C) NO_DUPLICATES
D) DIFFERENT

Answer:

A) DISTINCT

Explanation:

The DISTINCT keyword is used in SQL to return unique values in the output, eliminating any duplicate records.

3. What does the SQL LIKE query do?

A) Matches only the exact string
B) Matches by type
C) Matches a pattern
D) Matches the range

Answer:

C) Matches a pattern

Explanation:

The LIKE query in SQL is used to match a specified pattern in a column.

4. Which of the following SQL statements will update the "salary" column in the "employees" table for the employee with "employee_id" 102?

A) UPDATE employees SET salary=5000 WHERE employee_id=102;
B) MODIFY employees SET salary=5000 WHERE employee_id=102;
C) SAVE employees SET salary=5000 WHERE employee_id=102;
D) CHANGE employees SET salary=5000 WHERE employee_id=102;

Answer:

A) UPDATE employees SET salary=5000 WHERE employee_id=102;

Explanation:

The SQL UPDATE statement is used to modify the existing records in a table.

5. Which of the following statements will delete all records from the "employees" table?

A) DELETE * FROM employees;
B) DELETE FROM employees;
C) TRUNCATE employees;
D) Both B and C

Answer:

D) Both B and C

Explanation:

Both DELETE FROM and TRUNCATE statements will delete all records from a table. However, they work differently; DELETE logs individual row deletes, while TRUNCATE de-allocates data pages and is more efficient for large tables.

6. Which of the following is not a type of SQL constraint?

A) FOREIGN KEY
B) PRIMARY KEY
C) UNIQUE KEY
D) SECONDARY KEY

Answer:

D) SECONDARY KEY

Explanation:

There is no constraint called SECONDARY KEY in SQL. Constraints are used to specify rules for the data in a table.

7. What is the default sorting mode of the ORDER BY clause in SQL?

A) Ascending
B) Descending
C) Random
D) Alphabetical

Answer:

A) Ascending

Explanation:

The default sorting mode of the ORDER BY clause in SQL is ascending.

8. In SQL, which command is used to remove a table from a database?

A) REMOVE TABLE
B) DELETE TABLE
C) DROP TABLE
D) TRUNCATE TABLE

Answer:

C) DROP TABLE

Explanation:

The DROP TABLE command is used to remove a table definition and all data, indexes, triggers, constraints, and permission specifications for that table.

9. What is the purpose of the SQL JOIN clause?

A) To concatenate strings
B) To retrieve rows from one or more tables
C) To summarize data
D) To sort data

Answer:

B) To retrieve rows from one or more tables

Explanation:

The SQL JOIN clause is used to combine rows from two or more tables based on a related column between them.

10. Which SQL clause is used to restrict the results of a query based on a condition?

A) SELECT
B) WHERE
C) CONDITION
D) RESTRICT

Answer:

B) WHERE

Explanation:

The WHERE clause in SQL is used to filter the results of a query based on one or more conditions.

11. Which of the following SQL statements will retrieve the highest salary from the "employees" table?

A) SELECT MAX(salary) FROM employees;
B) SELECT TOP(salary) FROM employees;
C) SELECT HIGHEST(salary) FROM employees;
D) SELECT TOP 1 salary FROM employees ORDER BY salary DESC;

Answer:

A) SELECT MAX(salary) FROM employees;

Explanation:

The MAX() function in SQL is used to return the maximum value of an expression in a SELECT statement.

12. What will the SQL statement "SELECT ROUND(123.4567, 2);" return?

A) 123.46
B) 123.45
C) 124
D) 123

Answer:

A) 123.46

Explanation:

The ROUND() function in SQL is used to round a number to a specified number of decimal places. In this case, it rounds to two decimal places.

13. Which SQL statement is used to extract data from a database?

A) EXTRACT
B) GET
C) SELECT
D) RETRIEVE

Answer:

C) SELECT

Explanation:

The SELECT statement is used in SQL to extract data from a database.

14. Which SQL function will be used to find the total number of rows in a table?

A) NUM()
B) COUNT()
C) SUM()
D) TOTAL()

Answer:

B) COUNT()

Explanation:

The COUNT() function is used in SQL to count the number of rows in a set of returned results.

15. Which SQL keyword is used to sort the results of a query in ascending order?

A) SORT BY
B) ORDER BY ASC
C) ALIGN BY
D) ORDER ASC

Answer:

B) ORDER BY ASC

Explanation:

The ORDER BY keyword is used in SQL to sort the results in ascending or descending order according to one or more columns. The default order is ascending.

16. Which SQL statement is used to return only different values?

A) SELECT DIFFERENT
B) SELECT DISTINCT
C) SELECT UNIQUE
D) SELECT VARIOUS

Answer:

B) SELECT DISTINCT

Explanation:

The SELECT DISTINCT statement is used to return only distinct (different) values.

17. Which SQL clause is used to provide detailed data while avoiding duplicate rows?

A) JOIN
B) INNER JOIN
C) OUTER JOIN
D) CROSS JOIN

Answer:

B) INNER JOIN

Explanation:

INNER JOIN is used to combine rows from different tables if the join condition is true, thus avoiding duplicates and providing detailed data.

18. What is the primary purpose of a SQL view?

A) To view the database schema
B) To simplify complex queries
C) To prevent SQL injections
D) To optimize the database

Answer:

B) To simplify complex queries

Explanation:

A view in SQL is a virtual table based on the result-set of an SQL statement. A view can contain all rows of a table or selected rows from one or more tables. Its primary purpose is to simplify complex queries.

19. Which of the following SQL statements will add a "birthdate" column to the "employees" table?

A) ADD COLUMN birthdate DATE TO employees;
B) ALTER TABLE employees ADD COLUMN birthdate DATE;
C) MODIFY TABLE employees ADD birthdate DATE;
D) UPDATE TABLE employees SET birthdate DATE;

Answer:

B) ALTER TABLE employees ADD COLUMN birthdate DATE;

Explanation:

The ALTER TABLE statement is used to add, delete, or modify columns in an existing table.

20. What does the SQL query "SELECT * FROM Employees WHERE NOT EXISTS (SELECT * FROM Managers WHERE Employees.EmployeeID = Managers.ManagerID);" do?

A) Selects all employees who are also managers
B) Selects all employees who are not managers
C) Selects all managers who are not employees
D) Selects all managers who are also employees

Answer:

B) Selects all employees who are not managers

Explanation:

This SQL query selects all rows from the "Employees" table where there is no corresponding entry in the "Managers" table, i.e., it selects all employees who are not managers.

21. Which SQL statement will create an index on the "employee_name" column in the "employees" table?

A) CREATE INDEX idx_employee_name ON employees(employee_name);
B) ADD INDEX employee_name ON employees;
C) CREATE INDEX ON employee_name FROM employees;
D) INDEX ON employees(employee_name);

Answer:

A) CREATE INDEX idx_employee_name ON employees(employee_name);

Explanation:

The CREATE INDEX statement is used to create indexes on columns in a table, which can improve query performance.

22. Which type of JOIN returns all records when there is a match in one of the tables?

A) INNER JOIN
B) OUTER JOIN
C) LEFT JOIN
D) CROSS JOIN

Answer:

B) OUTER JOIN

Explanation:

An OUTER JOIN returns all records when there is a match in either the left (LEFT OUTER JOIN) or the right (RIGHT OUTER JOIN) table records. A FULL OUTER JOIN returns all records when there is a match in one of the tables.

23. Which SQL function calculates the number of characters in a string?

A) LENGTH()
B) CHAR_LENGTH()
C) NUM_CHARS()
D) Both A and B

Answer:

D) Both A and B

Explanation:

Both LENGTH() and CHAR_LENGTH() functions are used to calculate the number of characters in a string in SQL.

24. What is the default ordering mode of the SQL ORDER BY statement?

A) Ascending
B) Descending
C) Alphabetical
D) Numerical

Answer:

A) Ascending

Explanation:

The default ordering mode of the SQL ORDER BY statement is ascending.

25. Which SQL clause is used with the GROUP BY clause to filter the results of a group?

A) WHERE
B) HAVING
C) ON
D) USING

Answer:

B) HAVING

Explanation:

The HAVING clause is used with the SQL GROUP BY clause to filter the results of a group based on a condition.


We hope this comprehensive practice test provides you with insight and confidence as you prepare for the Oracle Database SQL Certified Associate exam. Remember, practice makes perfect, so be sure to thoroughly review your answers and continue to test your knowledge with additional resources and real-world scenarios. Good luck!

Related MCQ (Multiple Choice Questions) :

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