JDBC Quiz Wipro

What is the main reason to wrap DriverManager.getConnection() in a DBUtil class?

• Avoid code duplication

• Improve query performance

• Reduce memory

• To use Hibernate

What happens if Class.forName("oracle.jdbc.driver.OracleDriver") is missing?

• JDBC will use MySQL driver

• Program crashes silently

• ClassNotFoundException is thrown

• Database connection remains open

Which JDBC component is responsible for executing SQL queries?

• Driver

• Connection

• ResultSet

• Statement / PreparedStatement

In a DAO pattern, which of these responsibilities is valid for dao.java file?

• Business logic

• REST API calls

• Direct database operations

• Model creation

What would be the correct return type in a DAO method fetching all users from DB?

• String[]

• List<UserBean>

• UserService

• void

What is the purpose of throws ClassNotFoundException in DBUtil?

• It enforces use of static block

• JDBC always throws it

• Ensures driver loading failure is reported

• Forces compilation error

Which design pattern is most suitable for writing DBUtil?

• Builder

• Decorator

• Singleton

• Observer

If DBUtil returns null for connection, what might be the cause?

• Port mismatch

• Driver missing

• Wrong DB name

• All of the above

What does this DAO snippet do?

ps = conn.prepareStatement("DELETE FROM emp WHERE id = ?");

ps.setInt(1, 101);

int rows = ps.executeUpdate();

• Throws SQLException

• Deletes all rows

• Deletes employee with ID 101

• Prepares a SELECT

Which DAO method signature is best practice to retrieve a record?

• String getEmp()

• ResultSet getEmp()

• void getEmp(int id)

• UserBean getEmpById(int id)