user: Question: What was the day of vacancy for Vitória de Guimarães?
Columns: ['Team', 'Outgoing manage', 'Manner', 'Date of vacancy', 'Incoming manager', 'Date of appointment']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Académica de Coimbra', 'Artur Jorge', 'Resigned', '28 August 2003', 'Vítor Oliveira', '28 August 2003']
SQL:

assistant: SELECT "Date of vacancy" FROM "Table" WHERE "Team" = 'Vitória de Guimarães';