user: Question: What is every trigram when direction is Northwest?
Columns: ['Direction', 'Number', 'Trigram', '24 Mountains', 'Bearing / Degrees', 'Nature']
Types: ['text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['South', 9.0, 'Li 离 ☲', 'Bing 丙 Wu 午 Ding 丁', '157.6 - 172.5 172.6 - 187.5 187.6 - 202.5', 'Yang Yin Yin']
SQL:

assistant: SELECT "Trigram" FROM "Table" WHERE "Direction" = 'Northwest';