Table: coaches_changes
Columns: team
outgoing_head_coach
manner_of_departure
date_of_vacancy
position_in_table
incoming_head_coach
date_of_appointment

Question: If the position in table is 10th, and the manner of departure was resigned, what was the date of vacancy?
SQL: SELECT "date_of_vacancy" FROM coaches_changes WHERE "manner_of_departure" = 'Resigned' AND "position_in_table" = '10th'

Question: If the incoming head coach is Carlos Azenha, what is the date of vacancy?
SQL: SELECT "date_of_vacancy" FROM coaches_changes WHERE "incoming_head_coach" = 'Carlos Azenha'

Question: If the team is união de leiria, what is the date of appointment?
SQL: SELECT "date_of_appointment" FROM coaches_changes WHERE "team" = 'União de Leiria'