LINQ

10 LINQ Queries Every C# Beginner Should Know

Introduction

When working with data in C#, developers often need to filter, sort, and search data. Writing complex loops and conditions can make code difficult to read.

To solve this problem, C# introduced LINQ (Language Integrated Query).

LINQ allows developers to query collections like arrays, lists, and databases using simple syntax.

In this article, we will learn 10 important LINQ queries that every beginner should know, with simple examples.

What is LINQ?

LINQ stands for Language Integrated Query.

It allows developers to write data queries directly inside C# code.

Example without LINQ

List<int> numbers = new List<int>() { 5, 10, 15, 20 };

foreach (var n in numbers)
{
    if (n > 10)
    {
        Console.WriteLine(n);
    }
}

Example using LINQ

var result = numbers.Where(n => n > 10);

LINQ makes the code shorter and easier to read.

1. Select All Data

LINQ can retrieve all items from a list.

List<string> names = new List<string>()
{
    "Rahul",
    "Amit",
    "Neha"
};

var result = names.ToList();

Output

  • Rahul

  • Amit

  • Neha

2. Filter Data Using Where

The Where() method filters data based on a condition.

List<int> numbers = new List<int>() { 10, 20, 30, 40 };

var result = numbers.Where(x => x > 20);

Output

  • 30

  • 40

3. Select Specific Data

The Select() method returns specific fields.

Example:

var result = numbers.Select(x => x);

This selects values from the collection.

4. Sort Data Using OrderBy

We can sort data in ascending order.

List<int> numbers = new List<int>() { 50, 20, 10, 40 };

var result = numbers.OrderBy(x => x);

Output

  • 10

  • 20

  • 40

  • 50

5. Sort Data Using OrderByDescending

This sorts data in descending order.

var result = numbers.OrderByDescending(x => x);

Output

  • 50

  • 40

  • 20

  • 10

6. Get First Item

Use First() to retrieve the first element.

var result = numbers.First();

Output

  • 10

7. Count Items

The Count() method counts the number of elements.

var total = numbers.Count();

Output

  • 4

8. Check Condition Using Any

Any() checks whether any item satisfies a condition.

bool result = numbers.Any(x => x > 30);

Output

  • True

9. Get Maximum Value

Use Max() to find the largest value.

var maxValue = numbers.Max();

Output

  • 50

10. Get Minimum Value

Use Min() to find the smallest value.

var minValue = numbers.Min();

Output

  • 10

Real Example Using LINQ with Objects

Suppose we have a Student class.

public class Student
{
    public int Id { get; set; }

    public string Name { get; set; }

    public int Marks { get; set; }
}

Create a list.

List<Student> students = new List<Student>()
{
    new Student{Id=1,Name="Rahul",Marks=80},
    new Student{Id=2,Name="Amit",Marks=60},
    new Student{Id=3,Name="Neha",Marks=90}
};

Find students with marks greater than 70.

var result = students.Where(s => s.Marks > 70);

Output

  • Rahul

  • Neha

Advantages of LINQ

LINQ provides several benefits.

Cleaner Code

Queries become easier to read.

Less Code

Developers write fewer lines of code.

Strong Typing

Errors are detected at compile time.

Easy Data Manipulation

Filtering and sorting become simple.

Conclusion

LINQ is one of the most powerful features in C#. It allows developers to query data using simple syntax and improves code readability.

In this article, we learned:

  • What LINQ is

  • Why it is useful

  • 10 important LINQ queries with examples
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