Updating an existing SQL Database with thousands of records
Plan on doing one UPDATE per change needed.  It might look like
UPDATE t SET president = 'Biden' WHERE president = 'Trump';

If someone has left the company but has not yet been replaced, that gets tricky.
Walking down the hierarchy also gets tricky.  You seem to have a lot of redundant info.  It might be better to have rows that have only
id, manager_id, employee_id, title

However, then you must walk through the &quot;tree&quot; of rows to get to the various levels of management.
However, however, this would let you have a different depth for different departments.  (Currently you have a very rigid number of columns.)
&quot;Thousands of records&quot; is not a big deal.  &quot;Millions&quot; begins to get interesting.  &quot;Billions&quot; would be challenging.  (But what company has a billion employees?)