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Departments.Name Employees.FName

HR James

HR John

HR Johnathon

Sales Michael

Tech NULL

So how does this work?

There are two tables in the FROM clause:

Id FName LName PhoneNumber ManagerId DepartmentId Salary HireDate

01-01-
1 James Smith 1234567890 NULL 1 1000
2002

23-03-
2 John Johnson 2468101214 1 1 400
2005

12-05-
3 Michael Williams 1357911131 1 2 600
2009

24-07-
4 Johnathon Smith 1212121212 2 1 500
2016

and

Id Name

1 HR

2 Sales

3 Tech

First a Cartesian product is created from the two tables giving an intermediate table.
The records that meet the join criteria (Departments.Id = Employees.DepartmentId) are
highlighted in bold; these are passed to the next stage of the query.

As this is a LEFT OUTER JOIN all records are returned from the LEFT side of the join
(Departments), while any records on the RIGHT side are given a NULL marker if they do not
match the join criteria. In the table below this will return Tech with NULL

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