The SQL GROUP BY clause can be used in a SELECT statement to collect data across multiple TABLES and group the results by one or more columns. here is how we can achieve this in LINQ TO SQL in simple form.
Here we use Customer and Order tables from NorthWind (Free DB We can play with).
Create the DataContext and write the query to select records from Customer and Order Tables. assign this result to customerRecords. now call the Extension method GropBy on customerRecords here we are gouping the result by customer Id. and then loop through the result .
Here is the output of the above program.