When does WHERE filtering occur? [duplicate]

Answer 1

Per MSDN.
Check the section titled Logical Processing Order of the SELECT statement

1. FROM
2. ON
3. JOIN
4. WHERE
5. GROUP BY
6. WITH CUBE or WITH ROLLUP
7. HAVING
8. SELECT
9. DISTINCT
10. ORDER BY
11. TOP

There is an important note at the end of the paragraph preceding this list.

Note that the actual physical execution of the statement is determined by the query processor and the order may vary from this list.