MCQs on LINQ and Lambda Expressions | Visual Basic .NET (VB.NET)

Test your knowledge of LINQ and lambda expressions in Visual Basic .NET (VB.NET) with these 30 multiple-choice questions. Covering LINQ to Objects, LINQ to XML, LINQ to SQL, and the use of lambda expressions, these questions are designed to help you master these advanced concepts and prepare for coding challenges. The answer key is provided at the end for your reference.

LINQ to Objects

1. What is the main purpose of LINQ in VB.NET?
   A) To perform file I/O operations
   B) To query and manipulate data in collections
   C) To design user interfaces
   D) To connect to a database
2. Which method is used to execute a LINQ query in VB.NET?
   A) Execute()
   B) ToList()
   C) RunQuery()
   D) ExecuteQuery()
3. How do you specify a condition in a LINQ query?
   A) Using a where clause
   B) Using an if statement
   C) Using a for loop
   D) Using a select statement
4. Which of the following is NOT a valid LINQ method for querying a collection in VB.NET?
   A) First()
   B) Select()
   C) Filter()
   D) OrderBy()
5. How would you retrieve all elements of a collection in ascending order using LINQ?
   A) collection.OrderBy()
   B) collection.OrderByDescending()
   C) collection.Select()
   D) collection.Where()

LINQ to XML and LINQ to SQL

6. Which LINQ method is used to parse an XML document in VB.NET?
   A) Load()
   B) Parse()
   C) SelectNodes()
   D) GetXML()
7. What does LINQ to XML allow you to do?
   A) Parse and query XML data
   B) Convert XML to JSON
   C) Create SQL queries
   D) Execute HTTP requests
8. Which LINQ operator is used to join XML data based on a condition?
   A) Join()
   B) Merge()
   C) Select()
   D) InnerJoin()
9. In LINQ to SQL, how do you query a database table?
   A) From table in context
   B) Select table from context
   C) Get table()
   D) Fetch table data()
10. Which class is used to represent a connection to the database in LINQ to SQL?
    A) DataContext
    B) SqlConnection
    C) SqlCommand
    D) DatabaseContext

Using Lambda Expressions

11. What is the purpose of lambda expressions in VB.NET?
    A) To define anonymous methods
    B) To create new classes
    C) To perform file I/O operations
    D) To build user interfaces
12. Which syntax represents a simple lambda expression in VB.NET?
    A) Function(x) x + 1
    B) (x) => x + 1
    C) (x, y) => x + y
    D) Sub(x, y) x + y
13. How would you use a lambda expression with the Where method in LINQ?
    A) collection.Where(Function(x) x > 10)
    B) collection.Where(x => x > 10)
    C) collection.Filter(Function(x) x > 10)
    D) collection.Select(Function(x) x > 10)
14. Which of the following is a correct lambda expression to return the square of a number?
    A) Function(x) x ^ 2
    B) Function(x) x * x
    C) Function(x) x + x
    D) Function(x) x – x
15. What is the return type of a lambda expression in VB.NET?
    A) Boolean
    B) Object
    C) Action
    D) It depends on the expression

General LINQ and Lambda Expressions

16. What does the Select method do in a LINQ query?
    A) Filters the collection based on a condition
    B) Projects each element of the collection
    C) Sorts the collection in ascending order
    D) Joins multiple collections
17. How do you perform a grouping operation in LINQ?
    A) Use the GroupBy() method
    B) Use the Group() method
    C) Use the Filter() method
    D) Use the GroupElements() method
18. What is the result of applying the Distinct() method to a collection?
    A) It removes all duplicates
    B) It sorts the collection
    C) It filters elements based on a condition
    D) It groups the collection
19. Which LINQ method is used to return the first element in a collection that matches a condition?
    A) First()
    B) Single()
    C) FirstOrDefault()
    D) Find()
20. Which of the following operations can be performed using LINQ to SQL?
    A) Insert, Update, Delete
    B) Only Select queries
    C) Only Insert operations
    D) Only Delete operations
21. Which operator is used in LINQ to SQL for performing a left join?
    A) Join()
    B) LeftJoin()
    C) GroupJoin()
    D) InnerJoin()
22. What is the purpose of the Aggregate() method in LINQ?
    A) To perform a complex aggregation operation
    B) To filter elements
    C) To sort the collection
    D) To convert the collection to an array
23. Which of the following is a method for sorting data in LINQ?
    A) OrderBy()
    B) Select()
    C) GroupBy()
    D) FilterBy()
24. Which LINQ method is used to concatenate two collections?
    A) Concat()
    B) Merge()
    C) Combine()
    D) Join()
25. In LINQ, which method is used to count the number of elements in a collection that satisfy a condition?
    A) Count()
    B) Sum()
    C) Where()
    D) Filter()
26. What type of expression does a lambda function return?
    A) Delegate
    B) Value type
    C) Method
    D) Reference type
27. How do you create a lambda expression that takes two parameters and returns their product?
    A) (x, y) => x * y
    B) Function(x, y) x * y
    C) (x, y) x + y
    D) (x) x ^ 2
28. Which of the following is true about lambda expressions?
    A) They can be used as parameters to methods
    B) They must be named
    C) They cannot be assigned to variables
    D) They are always static
29. Which method is used to join two sequences in LINQ?
    A) Join()
    B) Combine()
    C) Merge()
    D) Concat()
30. What does the Take() method in LINQ do?
    A) Limits the number of elements returned
    B) Removes elements from the collection
    C) Groups the collection
    D) Filters the collection

Answer Key