Question

the link is
http://www.sqlcommands.net/sql+join/

i would like to know if it would work if it were

SELECT Weather.City
FROM Weather
WHERE Weather.City = State.City

meaning select all those cities “from weather” which belong in the state table

will the above work if not then why?

Answer 1

or, as an alternative (using yr english sentence as a guide):

SELECT City                -- select all those cities
FROM Weather               -- "from weather"
Where City In              -- which 
  (Select City From State) -- belong in the state table