Visual representation of SQL Joins

Figure: This image from Code project shows Inner join, Left join, Full outer join And Right join in visual form.

Some join examples

C# Inner Join

IEnumerable<string> query = from employee in employees
                                join student in students
                                on new { employee.FirstName, employee.LastName }
                                equals new { student.FirstName, student.LastName }
                                select employee.FirstName + " " + employee.LastName;

C# Inner Join

var query = from person in people
                join pet in pets on person equals pet.Owner
                select new { OwnerName = person.FirstName, PetName = pet.Name };

C# Left Outer Joins

var query = from person in people
                join pet in pets on person equals pet.Owner into gj
                from subpet in gj.DefaultIfEmpty()
                select new { person.FirstName, PetName = (subpet == null ? String.Empty : subpet.Name) };