What annotation is used in Spring Boot to expose a method as a REST API endpoint?

• @Service

• @RestController

• @Repository

• @RequestMapping

Answer explanation

The @RestController annotation in Spring Boot is used to define a controller that handles RESTful web services. It combines @Controller and @ResponseBody, making it ideal for exposing methods as REST API endpoints.

Which annotation is used to bind path variables in a URL to method parameters in Spring Boot?

• @PathVariable

• @RequestParam

• @RequestBody

• @Entity

Answer explanation

The @PathVariable annotation in Spring Boot is used to extract values from the URI path and bind them to method parameters, making it the correct choice for this question.

To fetch a list of employees based on their department, which SQL query would you use?

• SELECT * FROM employees WHERE department = 'HR';

• UPDATE employees SET department = 'HR';

• DELETE FROM employees WHERE department = 'HR';

• INSERT INTO employees (department) VALUES ('HR');

Answer explanation

The correct choice is 'SELECT * FROM employees WHERE department = 'HR';' because it retrieves all employees in the HR department. The other options modify or delete data instead of fetching it.

What annotation is used to define a primary key in a JPA entity?

• @Entity

• @Id

• @GeneratedValue

• @Table

Answer explanation

The @Id annotation is used in JPA to specify the primary key of an entity. It uniquely identifies each instance of the entity, making it essential for database operations.

A client sends a POST request to /products with product details. How would you represent the inserted product in the database using SQL?

• INSERT INTO products (name, price) VALUES ('Phone', 1000);

• SELECT * FROM products;

• DELETE FROM products WHERE name = 'Phone';

• UPDATE products SET price = 1000 WHERE name = 'Phone';

Answer explanation

The correct choice is 'INSERT INTO products (name, price) VALUES ('Phone', 1000);' as it accurately represents adding a new product with the specified details into the database.

What is the purpose of the @RequestBody annotation in Spring Boot?

• To map HTTP request body to a Java object

• To bind query parameters to method arguments

• To define a database entity

• To log HTTP requests

Answer explanation

The @RequestBody annotation in Spring Boot is used to map the HTTP request body to a Java object, allowing for easy data transfer between the client and server. This makes it essential for handling JSON or XML payloads.

Which command is used to create a database in MySQL?

• CREATE TABLE database_name;

• CREATE DATABASE database_name;

• USE database_name;

• INSERT INTO database_name;

Answer explanation

The correct command to create a database in MySQL is 'CREATE DATABASE database_name;'. The other options are either for creating tables, selecting databases, or inserting data, not for creating a database.

You want to ensure that the email column in a users table is always unique. Which SQL command would you use?

• ALTER TABLE users ADD CONSTRAINT email_unique UNIQUE (email);

• SELECT DISTINCT email FROM users;

• CREATE TABLE users (email VARCHAR(255) UNIQUE);

• Both a and c

Answer explanation

To ensure the email column is unique, you can use 'ALTER TABLE users ADD CONSTRAINT email_unique UNIQUE (email);' or define it during table creation with 'CREATE TABLE users (email VARCHAR(255) UNIQUE);'. Thus, both a and c are correct.

Which annotation is used to create a repository in Spring Boot?

• @Controller

• @RestController

• @Repository

• @Service

Answer explanation

The @Repository annotation is used in Spring Boot to indicate that a class is a repository, which is responsible for data access. It provides a mechanism for encapsulating storage, retrieval, and search behavior, making it the correct choice.

To update a user's phone number in the database, which SQL query would you use?

• UPDATE users SET phone = '1234567890' WHERE id = 1;

• SELECT * FROM users WHERE phone = '1234567890';

• INSERT INTO users (phone) VALUES ('1234567890');

• DELETE FROM users WHERE phone = '1234567890';

Answer explanation

The correct SQL query to update a user's phone number is 'UPDATE users SET phone = '1234567890' WHERE id = 1;'. This command modifies the phone number for the user with id 1 in the 'users' table.