_user = session.get('user')
cursor.execute("SELECT name, position, team from player_position_team WHERE assigned_to = _user")
Should be:
cursor.execute("SELECT name, position, team from player_position_team WHERE assigned_to = %s", (session.get('user')))
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…