I've come accross queries like this one previously but never got the
time to carefully study them form some book.

SELECT 1 WHERE 1 = 1


1) What do queries like these mean? From common sense, I can deduce
that it is some kind of a test for a boolean value, but the result is
already deterministic in the above case (true).

What use is such a query for?

2) What dialect of SQL (ANSI/T-SQL) does MS-SQL Server use?