Question:
I’ve archived/purged a few thousand rows of unnecessary data, but the disk space reading hasn’t changed. Do I need to use the ALTER TABLE command to reclaim empty space from deleted rows?

Answer:
When rows are deleted, the space is not reclaimed until the table is rebuilt. An easy way is to alter the primary index to cluster. This rebuilds the table with the rows placed physically in the order of the primary key. Use this format:

ALTER INDEX  to cluster;