The term 3-value logic pretty obviously implies the behavior of operators as they relate to NULL, not just the fact that data is nullable, of course. AFAIK MyS

The term 3-value logic pretty obviously implies the behavior of operators as they relate to NULL, not just the fact that data is nullable, of course. AFAIK MySQL, Oracle, and SQL Server don't have the Boolean datatype as a variable/column type - only Bit, which lacks boolean semnatics, and so Booleans are not considered data values, and therefore can't be used with IS NULL or COALESCE.