Linq Syntax and Query – How to write Linq Syntax

In this tutorial, you will learn:
  1. Linq Syntax and Query
  2. How to write Linq Query
  3. Query Syntax and Method Syntax
There are 2 types of LINQ Syntax, which you need to learn:
  1. Query Syntax
  2. Method Syntax

Query Syntax

Query Syntax is easy to learn. It has SQL like query syntax but it does not support all query operators in LINQ. Method Syntax is the more powerful way to write LINQ queries and it is also a standard way to write LINQ syntax.

Define

From <range variable> in <IEnumerable<T> or IQueryable<t> collection>
<standard query operators> <lambda expression>
<select or groupBy operator> <result formation>
Note: LINQ query always returns a list of items.

Programming Example 1

In this example, I am going to create a simple product list and then access all the items using the LINQ query. This is a simple console example.

using System;
using System.Collections.Generic;
using System.Linq;

namespace LinqExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Creating List
            IList<string> productList = new List<string>()
            {
                "Hard Disk",
                "Monitor",
                "SSD Disk",
                "RAM",
                "Processor",
                "Bluetooth",
                "Keyboard & Mouse"
            };

            var result = from s in productList                         
                         select s;

            foreach(string str in result)
            {
                Console.WriteLine(str.ToString());
            }

            Console.ReadKey();
        }
    }
}
Output
Hard Disk
Monitor
SSD Disk
RAM
Processor
Bluetooth
Keyboard & Mouse

_

Programming Example 2: Filtering Result

In the previous example, you executed your first LINQ query that returned all the item from the list. In this example, we will move one step forward and filter result using where clause.

using System;
using System.Collections.Generic;
using System.Linq;

namespace LinqExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // Creating List
            IList<string> productList = new List<string>()
            {
                "Hard Disk",
                "Monitor",
                "SSD Disk",
                "RAM",
                "Processor",
                "Bluetooth",
                "Keyboard & Mouse"
            };

            var result = from s in productList
                         where s.Contains("Disk")                         
                         select s;

            foreach(string str in result)
            {
                Console.WriteLine(str.ToString());
            }

            Console.ReadKey();
        }
    }
}
Output:
Hard Disk
SSD Disk
_

Summary

If you have executed program successfully then congratulations because you have crossed half way of LINQ. Once you know how to write LINQ syntax, it becomes very easy to learn LINQ methods and extensions. This chapter teaches you LINQ Query Syntax and in the next chapter, you will learn LINQ Method Syntax.

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