Example of three valued logic in SQL Server

Question

I understand that SQL uses three valued logic but I am having trouble understanding how to use this in practice, especially why TRUE || NULL = True and FA

Answer 1

True && NULL is neither True or False. It's just NULL.

Whether that will evaluate as True, False, or an Error in a boolean expression depends on what happens on your system when you evaluate NULL by itself as a boolean. Sql Server will do everything it can to avoid choosing, but when forced you'll pretty much never see a positive (True) result.