帆软直接是
weekday(日期) 这样取到是数字,0-6,星期天是0
要显示直接星期几格式,那就是 format(日期,"EEEEE")
A2 是完整的日期格式
switch(weekday(A2),0,"星期天",1,"星期一",2,"星期二",3,"星期三",4,"星期四",5,"星期五",6,"星期六")