50 Oracle Database Foundations Practice Questions: Question Bank 2025

What is the primary purpose of a database management system (DBMS)?

In a relational database, which term describes a single characteristic or attribute of an entity?

Which SQL statement is used to retrieve data from one or more tables in an Oracle database?

A database administrator needs to ensure that employee salaries in the EMPLOYEES table cannot be negative values. Which database constraint should be used?

Which Oracle Database component is responsible for managing memory structures and background processes?

What is the correct order of execution for clauses in a SQL SELECT statement?

In Oracle Database architecture, what is the purpose of the System Global Area (SGA)?

A developer writes the following SQL query: SELECT * FROM employees WHERE department_id = NULL; The query returns no rows even though there are employees with NULL department_id values. What is the problem?

An organization needs to model a many-to-many relationship between STUDENTS and COURSES, where each student can enroll in multiple courses and each course can have multiple students. What is the best database design approach?

During a database transaction, a user executes several DML statements (INSERT, UPDATE, DELETE). Before completing the transaction, the user decides to undo all changes made during this session. Which SQL command should be used?

Which SQL statement is used to permanently save changes made during a transaction?

What is the purpose of the Oracle Database instance?

A database administrator needs to remove all rows from a table quickly without generating undo information and while keeping the table structure intact. Which command should be used?

Which component of the System Global Area (SGA) stores recently executed SQL statements and their execution plans to improve performance?

A developer writes the following query: SELECT * FROM employees WHERE department_id = NULL; No rows are returned even though NULL values exist in the department_id column. What is the problem?

What is the primary purpose of a database checkpoint in Oracle Database?

Which constraint would you use to ensure that all values in a column are unique and that the column cannot contain NULL values?

A query joins three tables: CUSTOMERS, ORDERS, and PRODUCTS. The developer wants to retrieve all customers, including those who have never placed an order, along with their order details if they exist. Which join type is most appropriate?

A database contains a table with millions of rows. Users frequently query data based on a specific date range in the ORDER_DATE column, but queries are running slowly. What database object would most effectively improve query performance for these date-based searches?

An application developer needs to ensure that when a record is deleted from the DEPARTMENTS table, all related records in the EMPLOYEES table are automatically deleted as well. Which database feature should be implemented?

Which SQL statement is used to remove all rows from a table while maintaining the table structure and allowing for rollback?

A database administrator needs to ensure that committed transactions are permanently saved even in the event of a system failure. Which Oracle Database component is primarily responsible for this functionality?

Which constraint ensures that a column cannot contain NULL values and that each value in the column is unique across all rows?

A developer writes a query: SELECT employee_id, salary FROM employees WHERE department_id = 50 ORDER BY salary DESC; What type of operation is the ORDER BY clause performing?

In an Oracle Database, what is the primary purpose of the Database Buffer Cache within the SGA?

A query returns the error 'ORA-01722: invalid number'. The query is: SELECT * FROM products WHERE product_id = '100A'; Given that product_id is defined as NUMBER(10), what is the cause of this error?

Which statement best describes the relationship between a tablespace and data files in Oracle Database architecture?

A database has tables CUSTOMERS (customer_id PK, name) and ORDERS (order_id PK, customer_id FK, order_date). What will happen if you attempt to execute: DELETE FROM customers WHERE customer_id = 100; when there are orders associated with customer_id 100 and no ON DELETE CASCADE is defined?

During database instance startup, what is the correct sequence of stages that occur?

A developer needs to retrieve employees who earn more than the average salary in their department. Which query correctly accomplishes this using a correlated subquery?

A database administrator needs to ensure that a table's primary key values are automatically generated in sequential order. Which database object should be used?

Which SQL clause is used to filter the results of aggregate functions such as COUNT, SUM, or AVG?

In Oracle Database architecture, what is the primary purpose of the System Global Area (SGA)?

A developer executes a DELETE statement that removes 500 rows from a table but does not issue a COMMIT. What happens to the deleted data?

Which component of the Oracle Database instance is responsible for writing modified data blocks from the database buffer cache to the data files?

A query needs to retrieve all employees who work in either the Sales or Marketing departments. Which SQL operator would be most efficient for this requirement?

An application developer needs to create a constraint that ensures the salary column in an EMPLOYEES table is always greater than zero. Which type of constraint should be used?

A company's database stores customer information with a CUSTOMERS table and order information in an ORDERS table. The business requires that when a customer record is deleted, all associated orders must also be automatically deleted. What database feature accomplishes this?

A database has three tables: DEPARTMENTS, EMPLOYEES, and PROJECTS. You need to write a query that returns all departments along with the count of employees in each department, including departments with no employees. Which type of join and aggregate function combination is required?

During database operation, the Log Writer (LGWR) process fails to write to the online redo log files. What is the immediate consequence of this failure?

A database administrator needs to view the structure of the EMPLOYEES table, including column names, data types, and nullable constraints. Which command should be used?

What is the purpose of the System Global Area (SGA) in Oracle Database architecture?

Which SQL statement would create a table that automatically generates unique sequential numbers for the employee_id column?

A user executes a query that takes an unusually long time to complete. Which Oracle memory structure would cache the query results to improve performance for subsequent identical queries?

What type of relationship exists when each record in Table A can be associated with multiple records in Table B, and each record in Table B can be associated with multiple records in Table A?

A developer needs to retrieve all employees whose salary is between 50000 and 100000, inclusive. Which SQL clause should be used for optimal readability?

An application requires that certain data changes be automatically logged whenever an UPDATE operation occurs on the PRODUCTS table. Which database object should be implemented?

Which background process in Oracle Database is responsible for writing modified data blocks from the database buffer cache to the data files?

A database designer is normalizing a database and needs to eliminate partial dependencies where non-key attributes depend on only part of a composite primary key. Which normal form is being achieved?

A database administrator needs to recover a database after a system failure. The database was running in ARCHIVELOG mode. Which combination of files is essential for complete recovery to the point of failure?