Mysql – SQL: Query multiple tables with a conditional result field (Sorry I don't even know how to ask it correctly)
Taking into account the following example tables: USERS: id_user name 1 Paul 2 Caroline TRAVEL: id_travel id_user 1 1 2 1 3 2 TRAVEL_DAYS: id_tdays id_travel day_has_activities 1 1 no 2 1 no 3 1 yes 4 2 no 5…