Aspiring data scientists and analytics professionals often find themselves facing a daunting challenge: the interview process. Companies like BNY Mellon, renowned for their expertise in finance and investment management, demand a robust understanding of data science and analytics principles. To help you prepare effectively, we’ve compiled a comprehensive guide featuring common interview questions and detailed answers tailored specifically for BNY Mellon interviews.
Table of Contents
SQL server and DotNet Interview Questions
Question: What is normalization, and why is it important in database design?
Answer: Normalization is the process of organizing data in a database to reduce redundancy and dependency. It ensures that data is stored logically to minimize redundancy and improve data integrity. Normalization reduces the chances of anomalies occurring in a database.
Question: What is a stored procedure, and how is it different from a function?
Answer: A stored procedure is a precompiled collection of SQL statements that perform a specific task. It is stored in the database and can be executed multiple times without recompiling. A function, on the other hand, returns a value and can be used in SQL statements wherever an expression can be used.
Question: What is an index, and why are they used in databases?
Answer: An index is a database object that improves the speed of data retrieval operations on a table at the cost of additional space and decreased performance on data modification operations. Indexes are used to quickly locate data without having to search every row in a table.
Question: Explain the difference between clustered and non-clustered indexes.
Answer: A clustered index determines the physical order of data in a table and can be created on only one column per table. Non-clustered indexes don’t affect the physical order of the table’s data and can be created on multiple columns. Each table can have only one clustered index but multiple non-clustered indexes.
Question: What is a deadlock, and how can it be avoided?
Answer: A deadlock occurs when two or more processes are waiting for resources held by each other, resulting in a cyclic dependency where neither process can proceed. Deadlocks can be avoided by ensuring that transactions lock resources in a consistent order, keeping transactions short avoiding long-running transactions, and using proper isolation levels.
Question: What is the Common Language Runtime (CLR) in .NET?
Answer: The CLR is the runtime environment provided by the .NET Framework to execute .NET applications. It provides features such as automatic memory management (garbage collection), exception handling, security, and interoperability with native code.
Question: Explain the difference between value types and reference types in C#.
Answer: Value types store their data, and reference types store a reference to the data. Value types are stored on the stack, whereas reference types are stored on the heap. Examples of value types include int, float, and struct, while examples of reference types include class, interface, and delegate.
Question: What is the difference between abstraction and encapsulation?
Answer: Abstraction is the process of hiding the implementation details and showing only the necessary features of an object. Encapsulation is the bundling of data and methods that operate on the data into a single unit (class) and restricting access to some of the object’s components.
Question: What is ASP.NET MVC, and how does it differ from ASP.NET Web Forms?
Answer: ASP.NET MVC is a web development framework for building web applications using the Model-View-Controller architectural pattern. It provides more control over the HTML markup and supports test-driven development. ASP.NET Web Forms, on the other hand, follows a more event-driven programming model and provides server controls that abstract the HTML markup.
Question: What are the advantages of using Entity Framework for database access in .NET?
Answer: Entity Framework is an Object-Relational Mapping (ORM) framework that simplifies database access in .NET applications. Its advantages include reduced development time, improved productivity, automatic generation of SQL queries, support for LINQ (Language Integrated Query), and database independence.
PowerBI Interview Questions
Question: What is Python, and why is it popular for data science and software development?
Answer: Python is a high-level, interpreted programming language known for its simplicity and readability. It is popular for data science due to its rich ecosystem of libraries (such as NumPy, Pandas, and Matplotlib) and for software development due to its versatility and ease of use.
Question: Explain the difference between Python 2 and Python 3.
Answer: Python 2 and Python 3 are two major versions of the Python programming language. Python 3 introduced several syntactical and semantic changes to improve the language’s consistency and remove redundancies present in Python 2. Python 2 reached its end of life in 2020, and Python 3 is the recommended version for all new projects.
Question: What is PEP 8, and why is it important in Python development?
Answer: PEP 8 is the Python Enhancement Proposal that establishes guidelines for writing clean, readable Python code. It covers topics such as indentation, naming conventions, code layout, and style practices. Adhering to PEP 8 ensures consistency across Python codebases and improves code maintainability.
Question: What are the differences between lists and tuples in Python?
Answer: Lists are mutable sequences of elements, meaning their contents can be modified after creation. Tuples, on the other hand, are immutable sequences, meaning their contents cannot be changed after creation. Lists are defined using square brackets [ ], while tuples are defined using parentheses ( ).
Question: Explain the concept of a Python decorator.
Answer: A decorator is a function that takes another function as input and extends or modifies its behavior without changing its source code. Decorators are commonly used for adding logging, authentication, or caching functionality to functions, methods, or classes.
Question: What are lambda functions, and when are they used in Python?
Answer: Lambda functions, also known as anonymous functions, are small, single-expression functions defined without a name. They are typically used in situations where a simple function is needed for a short period, such as when passing a function as an argument to higher-order functions like map(), filter(), or sorted().
Question: What is the purpose of the __init__ method in Python classes?
Answer: The __init__ method is a special method in Python classes used for initializing object instances. It is called automatically when a new instance of the class is created and is used to set up initial object attributes or perform any necessary setup tasks.
Question: How does exception handling work in Python?
Answer: Exception handling in Python allows developers to handle errors or exceptional situations gracefully without crashing the program. It involves using try, except, else, and finally blocks to catch and handle exceptions that may occur during program execution.
Shell Scripting and VBA Interview Questions
Question: What is a shell script, and what are its advantages?
Answer: A shell script is a program written in a scripting language interpreted by a shell, such as Bash in Unix/Linux or PowerShell in Windows. Its advantages include automating repetitive tasks, streamlining command-line operations, and improving productivity.
Question: Explain the difference between a shell and a terminal.
Answer: A shell is a command-line interpreter that allows users to interact with the operating system by executing commands. A terminal, on the other hand, is a text-based interface through which users interact with the shell. Terminals provide a way to input commands and view their output.
Question: What is the shebang line, and why is it used in shell scripts?
Answer: The shebang line, represented as #! is a special syntax at the beginning of a shell script that specifies the path to the shell interpreter to use. It tells the operating system which interpreter to use when executing the script. For example, #!/bin/bash indicates that the script should be executed using the Bash shell.
Question: How do you pass arguments to a shell script?
Answer: Arguments can be passed to a shell script when invoking it from the command line. They are accessible within the script using positional parameters like $1, $2, etc. For example, running ./script.sh arg1 arg2 will make $1 equal to “arg1” and $2 equal to “arg2” within the script.
Question: What is a pipeline in shell scripting, and how does it work?
Answer: A pipeline is a sequence of commands connected by the pipe operator |, where the output of one command is passed as input to the next command. It allows for the chaining of commands, enabling complex data processing operations. For example, command1 | command2 passes the output of command1 as input to command2.
Question: What is VBA, and where is it commonly used?
Answer: VBA (Visual Basic for Applications) is a programming language developed by Microsoft for automating tasks within and integrating with other Microsoft applications like Excel, Word, Access, and Outlook. It allows users to write scripts to automate repetitive tasks, customize functionality, and extend the capabilities of these applications.
Question: Explain the difference between Sub procedures and Function procedures in VBA.
Answer: Sub procedures (Subs) are procedures that perform an action but do not return a value, while Function procedures (Functions) are procedures that perform an action and return a value. Subs are typically used for executing tasks or procedures, while Functions are used for calculations or returning specific values.
Question: What is the Object Browser in VBA, and how is it useful?
Answer: The Object Browser is a tool in the VBA editor that allows users to browse through the available objects, properties, methods, and constants in the libraries referenced by the VBA project. It is useful for exploring the functionality of different objects, understanding their properties and methods, and writing code more efficiently.
Question: How do you declare variables in VBA, and what are the different data types available?
Answer: Variables in VBA are declared using the Dim statement followed by the variable name and optionally the data type. VBA supports various data types, including Integer, Long, Double, String, Boolean, Date, Object, and Variant.
Question: Explain the concept of the Excel object model in VBA.
Answer: The Excel object model in VBA represents the hierarchy of objects, properties, and methods available for interacting with Excel applications, workbooks, worksheets, ranges, charts, and other elements. It allows users to manipulate Excel data, perform calculations, format cells, create charts, and automate various tasks using VBA code.
Conclusion
Preparing for data science and analytics interviews at BNY Mellon requires a blend of technical proficiency, business acumen, and effective communication skills. By familiarizing yourself with common interview questions and practicing thoughtful responses, you can confidently navigate the interview process and showcase your suitability for these dynamic roles within one of the world’s leading financial institutions. Good luck!
