How can I reference a single table multiple times in the same query?

Question

Sometimes I need to treat the same table as two separate tables. What is the solution?

Answer 1

You can reference, just be sure to use a table alias

select a.EmployeeName,b.EmployeeName as Manager
from Employees A
join Employees B on a.Mgr_id=B.Id

Answer 2

Use an alias like a variable name in your SQL:

select
    A.Id,
    A.Name,
    B.Id as SpouseId,
    B.Name as SpouseName
from
    People A
    join People B on A.Spouse = B.id