70+ DOT NET Developer Interview Questions and Answers for Freshers

No, only one primary key can be defined in a SQL table.

• Primary key ensures uniqueness of each record in a table.

• A table can have only one primary key constraint.

• However, a composite primary key can be created using multiple columns.

The components of .NET Framework include Common Language Runtime, Class Library, and ASP.NET.

• Common Language Runtime (CLR) - manages memory, security, and execution of code

• Class Library - provides a set of reusable classes and types for building applications

• ASP.NET - a web application framework for building dynamic web pages and web services

• Other components include ADO.NET, Windows Communication Foundation (WCF), Windows Presentation Foundation (WPF), and Windows Workflow Fou...read more

The optimal solution approach for the Travelling Salesman Problem involves using algorithms such as the Nearest Neighbor Algorithm and the 2-Opt Algorithm.

• The Nearest Neighbor Algorithm starts at a random city and selects the nearest unvisited city as the next stop.

• The 2-Opt Algorithm involves swapping two edges in the tour to see if it results in a shorter distance.

• Other algorithms include the Genetic Algorithm and the Simulated Annealing Algorithm.

• The optimal solution is no...read more

Query to find 4th highest salary

• Use the 'ROW_NUMBER' function to assign a rank to each salary

• Order the salaries in descending order

• Select the salary with rank 4

SELECT is used to retrieve data, DELETE is used to remove data, and UPDATE is used to modify data in SQL.

• SELECT is used to retrieve specific data from a database table.

• DELETE is used to remove specific data from a database table.

• UPDATE is used to modify existing data in a database table.

• Examples: SELECT * FROM table_name, DELETE FROM table_name WHERE condition, UPDATE table_name SET column_name = value WHERE condition

Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Characteristics include private constructor, static instance variable, static method to access instance, lazy initialization, and thread safety.

• Example: public class Singleton { private static Singleton instance; private Singleton() {} public static Singleton getInstance() { if (instance == null) { instance = new Singleton(); } return instance; }}

OOP is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• OOP focuses on creating reusable and modular code by organizing data and behavior into objects.

• Key principles of OOP include encapsulation, inheritance, and polymorphism.

• Examples of OOP languages include Java, C++, and C#.

• Applications of OOP include software development, game development, and web development.

The process for inserting data in ASP.NET MVC involves creating a model, a view, and a controller to handle the data insertion.

• Create a model class to represent the data you want to insert

• Create a view with form fields to input the data

• Create a controller action method to handle the form submission and insert the data into the database

• Use Entity Framework or other data access technologies to interact with the database

Abstract class is a class that cannot be instantiated and can have both abstract and non-abstract methods. Interface is a contract that a class must adhere to.

• Abstract class can have fields, constructors, and non-abstract methods, while interface cannot.

• A class can inherit only one abstract class, but can implement multiple interfaces.

• Abstract class can provide default implementations for some methods, while interface cannot.

• Abstract class is used when there is a need for com...read more

Sarah's speed is 7.2 km/h.

• Convert 600 meters to kilometers (600m = 0.6 km)

• Calculate the speed using the formula: Speed = Distance / Time

• Speed = 0.6 km / 5 minutes = 0.12 km/min

• Convert minutes to hours (1 hour = 60 minutes)

• Speed = 0.12 km/min * 60 min/hour = 7.2 km/h

Use LINQ to fetch data from the 'students' table in ascending order of 'studentid'.

• Use LINQ query syntax or method syntax to retrieve data from the 'students' table.

• Order the data by 'studentid' in ascending order using the 'OrderBy' or 'OrderByDescending' method.

• Ensure that the LINQ query is executed against the database to fetch the data.

Abstract classes are partially implemented classes that can have both abstract and non-abstract members. Interfaces are fully abstract classes that define a contract for implementing classes.

• Abstract classes can have constructors, fields, and non-abstract methods, while interfaces cannot.

• A class can inherit from only one abstract class, but it can implement multiple interfaces.

• Abstract classes can provide default implementations for some methods, while interfaces cannot.

• Inter...read more

The main difference is that .NET Core is cross-platform and open-source, while .NET Framework is Windows-only and closed-source.

• NET Core is cross-platform, while .NET Framework is Windows-only

• .NET Core is open-source, while .NET Framework is closed-source

• .NET Core is modular, allowing developers to include only the necessary libraries, while .NET Framework is monolithic

• NET Core is optimized for cloud-based applications, while .NET Framework is more suited for desktop applicat...read more

Abstract methods are methods without implementation in abstract classes, while interfaces are contracts that define methods.

• Abstract classes can have both abstract and non-abstract methods, while interfaces can only have abstract methods.

• A class can implement multiple interfaces, but can only inherit from one abstract class.

• Abstract classes can have constructors, while interfaces cannot.

• Interfaces can have properties, while abstract classes can have fields.

Difference between IEnumerable and IQueryable

• IEnumerable is used for in-memory collections while IQueryable is used for querying data from a database

• IEnumerable executes the query on the client-side while IQueryable executes the query on the server-side

• IQueryable supports deferred execution while IEnumerable does not

MVC is a software design pattern that separates an application into three interconnected components: Model, View, and Controller.

• Model represents the data and business logic of the application

• View is responsible for rendering the user interface

• Controller handles user input and updates the model and view accordingly

• MVC promotes separation of concerns and modularity

• Example: ASP.NET MVC framework

Create CRUD operations for name, email, and password input fields.

• Create a form with input fields for name, email, and password.

• Implement functions for Create, Read, Update, and Delete operations for each field.

• Use a database to store and retrieve the data.

• Example: Create operation - INSERT INTO users (name, email, password) VALUES ('John Doe', 'johndoe@example.com', 'password123');

Union combines and removes duplicates, Union All combines without removing duplicates.

• Union removes duplicates from the result set, while Union All does not.

• Union is slower than Union All because it has to perform an additional step to remove duplicates.

• Union is used when you want to combine two result sets and remove duplicates, while Union All is used when you want to combine two result sets without removing duplicates.

Abstract class can have implementation while interface cannot. Abstract class can have constructors while interface cannot.

• Abstract class can have method implementations while interface cannot.

• Abstract class can have fields while interface cannot.

• Abstract class can have constructors while interface cannot.

• Interfaces are used for multiple inheritance in C#.

• Abstract classes are used when some common functionality needs to be implemented for all derived classes.

A:D = 6:5

• First, find the common ratio between A and B, which is 3:4

• Then, use the ratios between B and C, and C and D to find the ratio between A and D

• Calculate the ratio A:D using the ratios found in the previous steps

NET is a software framework developed by Microsoft for building and running applications on Windows.

• NET is used for developing web applications, desktop applications, mobile applications, and services.

• It provides a large class library known as Framework Class Library (FCL) to support various programming languages.

• It allows interoperability between different programming languages such as C#, VB.NET, and F#.

• Examples of .NET technologies include ASP.NET, WPF, and Xamarin.

Binary search to find minimum element in sorted and rotated array.

• Perform binary search to find the pivot element where the array is rotated.

• Compare the pivot element with the first element to determine which half to search in.

• Continue binary search in the appropriate half to find the minimum element.

dotnet is a software framework developed by Microsoft for building and running applications on Windows.

• dotnet is a free, open-source framework

• It supports multiple programming languages like C#, F#, and Visual Basic

• It provides a common runtime environment for executing applications

• It includes a large class library for various functionalities

• dotnet Core is a cross-platform version of dotnet

Interfaces are a way to define a contract between classes, specifying methods and properties that must be implemented.

• Interfaces allow for polymorphism and loose coupling

• Classes can implement multiple interfaces

• Interfaces can inherit from other interfaces

• Examples include IDisposable, IEnumerable, and IComparable

Java is a programming language and Collection Framework is a set of classes and interfaces used to store and manipulate groups of objects.

• Java is an object-oriented programming language used to develop applications for various platforms.

• Collection Framework provides interfaces like List, Set, and Map to store and manipulate groups of objects.

• Examples of Collection Framework classes are ArrayList, HashSet, and HashMap.

Use bulk insert or batch processing to send large amounts of data through the database.

• Use bulk insert operations provided by the database management system.

• Consider using batch processing techniques to optimize performance.

• Use stored procedures or parameterized queries for efficient data transfer.

HtmlHelper is used to generate HTML controls in MVC views, while html is used for static HTML markup.

• HtmlHelper is a class in MVC that helps generate HTML controls with strongly-typed views

• HtmlHelper provides intellisense support and compile-time checking for HTML controls

• html is used for static HTML markup in MVC views

Async and await are keywords in C# that allow for asynchronous programming, making it easier to write code that doesn't block the main thread.

• Async is used to define a method as asynchronous, allowing it to run concurrently with other code.

• Await is used within an async method to pause execution until a task is complete, without blocking the main thread.

• Async and await are commonly used in scenarios such as making web requests, database operations, and file I/O.

• Example: async ...read more

Encapsulation is the process of hiding internal details and providing a public interface for accessing and manipulating data.

• Encapsulation helps in achieving data abstraction and data hiding.

• It allows for better control over the data by preventing direct access to it.

• Encapsulation promotes code reusability and maintainability.

• In object-oriented programming, encapsulation is implemented using classes and access modifiers.

• Example: A class with private variables and public metho...read more

Class and object programming example

• Classes are templates for objects

• Objects are instances of classes

• Classes define properties and methods

• Objects can access and modify properties and methods

• Example: Class - Car, Object - Honda Civic

MVC is a web application framework for building web pages, while WebAPI is a framework for building HTTP services.

• MVC is used for building web applications that return HTML views to the client.

• WebAPI is used for building HTTP services that return data in JSON or XML format.

• MVC has a view engine that generates HTML output, while WebAPI does not.

• MVC has a controller that handles user input and updates the model, while WebAPI has a controller that handles HTTP requests and retur...read more

SQL query to find the second maximum value in a table

• Use the MAX function to find the maximum value in the table

• Use the WHERE clause to exclude the maximum value

• Use the MAX function again to find the second maximum value

Value types store data directly, while reference types store a reference to the data

• Value types are stored on the stack and include simple types like int, float, struct

• Reference types are stored on the heap and include classes, interfaces, arrays

• Changing a value type variable does not affect other variables, while changing a reference type variable can affect other variables

• Example: int is a value type, while string is a reference type

OOPs (Object-Oriented Programming) is a programming paradigm based on the concept of objects, which can contain data in the form of fields and code in the form of procedures.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: The ability of different classes to be treated as instances of the same class through a common interface.

• Abstraction: Hidin...read more

SQL stands for Structured Query Language. It is a programming language used for managing and manipulating relational databases.

• SQL is used to create, modify, and retrieve data from databases.

• It is a standard language for interacting with databases.

• SQL statements are used to perform tasks such as inserting, updating, and deleting data.

• Examples of SQL commands include SELECT, INSERT, UPDATE, and DELETE.

• SQL is not case-sensitive, meaning keywords can be written in uppercase or l...read more

SQL Server joins are used to combine rows from two or more tables based on a related column between them.

• Inner Join: Returns rows when there is at least one match in both tables.

• Left Join: Returns all rows from the left table and the matched rows from the right table.

• Right Join: Returns all rows from the right table and the matched rows from the left table.

• Full Outer Join: Returns rows when there is a match in one of the tables.

• Self Join: Joining a table with itself to combin...read more

An object is an instance of a class that encapsulates data and behavior.

• An object is created from a class blueprint.

• It has state (data) and behavior (methods).

• Objects can interact with each other through method calls.

• Example: A car object can have properties like color and speed, and methods like start and stop.

MVC application authentication can be achieved using various methods like Forms Authentication, Windows Authentication, OAuth, etc.

• Use Forms Authentication for username/password based authentication

• Implement Windows Authentication for intranet applications

• Utilize OAuth for third-party authentication like Google, Facebook, etc.

Minimum jumps to reach end of an array can be calculated using dynamic programming approach.

• Use dynamic programming to keep track of minimum jumps needed to reach each index.

• Iterate through the array and update the minimum jumps for each index based on previous jumps.

• Return the minimum jumps needed to reach the end of the array.

Selectors in CSS are patterns used to select the elements you want to style on a web page.

• Selectors can target elements based on their tag name, class, ID, attributes, and more.

• Examples include: element selector (p), class selector (.example), ID selector (#example), attribute selector ([type='text']), etc.

Method is a block of code that performs a specific task and can be called by other parts of the program.

• Methods are used to break down complex programs into smaller, more manageable pieces.

• They can take input parameters and return values.

• Examples of methods in C# include Console.WriteLine() and Math.Max().

An interface is a contract that defines a set of methods and properties that a class must implement.

• An interface is a blueprint for a class

• It contains only the signatures of methods, properties, and events

• It does not provide implementation

• A class can implement multiple interfaces

• Interfaces are used to achieve abstraction and polymorphism

Inheritance is used in projects to promote code reusability, reduce redundancy, and improve maintainability.

• Inheritance allows for the creation of a hierarchy of classes where common attributes and methods can be defined in a base class and inherited by subclasses.

• It helps in promoting code reusability by allowing subclasses to inherit properties and methods from a base class, reducing redundancy in code.

• Inheritance also helps in improving maintainability as changes made to t...read more

Prime numbers are numbers that are only divisible by 1 and themselves.

• Start with 2, check if number is divisible by any number less than itself

• If not divisible, it is a prime number

• Use a loop to check all numbers less than the given number

• 1 is not a prime number

Constructor chaining is the process of calling one constructor from another constructor within the same class.

• Allows for reusing code and avoiding duplication

• Can be achieved using 'this' keyword in the constructor

• Example: public MyClass(int x) : this(x, 0) {}

CTE stands for Common Table Expressions, which is a temporary result set that can be referenced within a SELECT, INSERT, UPDATE, or DELETE statement.

• CTEs are defined using the WITH keyword in SQL.

• They help improve readability and maintainability of complex queries.

• CTEs can be recursive, allowing for hierarchical data querying.

• Example: WITH CTE AS (SELECT * FROM table_name) SELECT * FROM CTE;

• Example: WITH RECURSIVE CTE AS (SELECT * FROM table_name UNION ALL SELECT * FROM CTE) ...read more

Extension methods allow adding new methods to existing types without modifying the original type

• Extension methods are static methods that can be called as if they were instance methods of the extended type

• They are defined in static classes and must be in the same namespace as the extended type

• They are commonly used to add functionality to existing types or interfaces without modifying them directly