LINQ means Language Integrated Query and it was introduced in .NET Framework 3.5 to query the data from different data sources such as collections, generics, XML documents, SQL databases, etc. in both C# and VB.NET based on our requirements.
Generally, the LINQ will add a rich, standardized query syntax in .NET programming languages and it will allow the developers to write SQL style of queries within the code to interact with any type of data.
To perform LINQ related operations such as filtering, sorting, etc. on available data sources first, we need to import System.Linq namespace in our application.
In LINQ, we can write the queries in two ways.
In LINQ, to write the queries using query syntax the structure should be like as shown below.
from <variable> in <collection>
<where, joining, grouping, operators etc.> <lambda expression>
<select or groupBy operator> <format the results>
We need to follow this structure while writing the queries in LINQ. To learn more about Query syntax refer LINQ Query Syntax.
In LINQ, the method syntaxes will use extension methods of Enumerable or Queryable static classes.
Following is the example of using LINQ method syntaxes in visual basic.
Dim Num As Integer() = {1, 2, 3, 4, 5, 6, 7, 8, 9}
'LINQ Query Syntax to Print Numbers Greater than 3
Dim result As IEnumerable(Of Integer) = From numbers In Num Where numbers > 3 Selectnumbers
To learn more about method syntaxes in LINQ, refer LINQ Method Syntax.
To learn more about LINQ in C#, refer step by step LINQ Tutorial.