I've been in an argument with one of our devs that took an update statement with an inner join and made it a left join (because inner was missing some records somehow in the left table - tableB in ...

MS SQL has COALESCE as well. COALESCE is what you'll want to use unless you want to deal with NVL, ISNULL, and IFNULL (not to be confused with NULLIF) for the respective dbs.