Linq Joins in C# - Lemborco

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LINQ (Language Integrated Query) is a powerful technology that allows us to query data from different sources like collections, arrays, databases, XML files, and more. One of the essential features of LINQ is the ability to perform Joins between different data sources. In this lesson, we will discuss the different types of Joins in LINQ, including Inner Join, Left Join, Group Join, and more.

Inner Join:

An Inner Join is the most common type of Join in LINQ. It returns only the matching records from both tables. The syntax for Inner Join in LINQ is as follows:

var result = from table1 in dataSource1
             join table2 in dataSource2
             on table1.column equals table2.column
             select new { table1.column, table2.column };

In this syntax, dataSource1 and dataSource2 are the two data sources that are to be joined, column is the common field between the tables, and result is the variable that holds the joined data.

Left Join:

A Left Join returns all the records from the left table and only the matching records from the right table. The syntax for Left Join in LINQ is as follows:

var result = from table1 in dataSource1
             join table2 in dataSource2
             on table1.column equals table2.column into temp
             from t in temp.DefaultIfEmpty()
             select new { table1.column, t.column };

Group Join:

A Group Join returns a group of matching records from both tables. The syntax for Group Join in LINQ is as follows:

var result = from table1 in dataSource1
             join table2 in dataSource2
             on table1.column equals table2.column into temp
             select new { table1.column, temp };

Cross Join:

A Cross Join returns all possible combinations of the records from both tables. The syntax for Cross Join in LINQ is as follows:

var result = from table1 in dataSource1
             from table2 in dataSource2
             select new { table1.column, table2.column };

In this syntax, dataSource1 and dataSource2 are the two data sources that are to be joined, and result is the variable that holds the joined data.

In conclusion, LINQ Joins are a powerful feature that allows us to combine data from different sources based on a common field. The different types of Joins in LINQ include Inner Join, Left Join, Group Join, and Cross Join. By understanding the syntax and usage of these Joins, we can write efficient and effective LINQ queries to retrieve and manipulate data from multiple sources.

Inner Join:

Left Join:

Group Join:

Cross Join:

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