One NULL in the List and NOT IN Returns Nothing
NOT IN and NOT EXISTS read like the same thing. Find the rows that are not in that other set. They agree until the other set contains a NULL, at which point NOT IN returns…
ISNULL Truncates Your Replacement Value; COALESCE Doesn’t
ISNULL and COALESCE look like the same function wearing different names. Both take a value, both give you something else when that value is NULL. They differ in how they decide the type of what…
Double-Hyphen Comments Can Comment Out Your WHERE Clause
-- and /* */ both comment out T-SQL. The difference is where they stop. /* */ stops where you close it. -- runs to the end of the line,[2] and if there is no end…