20 Asked LINQ Interview Questions and Answers (2024)

Ques 1. What is LINQ?

Language-Integrated Query (LINQ) is a set of features in C# and VB.NET that allows you to write queries directly into your code.

Example:

var query = from x in myList where x > 5 select x;

Ques 2. Explain the difference between IEnumerable and IQueryable in LINQ.

IEnumerable is used for querying data from in-memory collections, while IQueryable is used for querying data from out-of-memory data sources like a database.

Ques 3. What is deferred execution in LINQ?

Deferred execution means that the execution of the query is delayed until the result is actually enumerated or a terminal operation is called.

Example:

var query = myList.Where(x => x > 5); // Execution is deferred until the result is enumerated.

Ques 4. Explain the concept of anonymous types in LINQ.

Anonymous types allow you to create objects without defining a formal class structure. They are often used in LINQ queries to return a subset of properties.

Example:

var result = from p in products select new { p.Name, p.Price };

Ques 5. What is the purpose of the 'let' keyword in LINQ?

The 'let' keyword allows you to create a new variable within a query and use it within the rest of the query.

Example:

var query = from x in myList let y = x * 2 select y;