T-SQL: Comparing Two Tables - Records that don't exist in second table

Question

If UNION ALL is an addition in T-SQL. What is the equivalent of subtraction?

For example, if I have a table PEOPLE and a table

Answer 1

SELECT
     P.*
FROM
     People P
LEFT OUTER JOIN Employees E ON
     E.ID = P.ID     -- Or whatever your PK-FK relationship is
WHERE
     E.ID IS NULL

For SQL Server this will probably be the most performant way that you can do it.