if(len(b1)=0,if(c1>a1,"逾期","正常"),if(b1>a1,"逾期","正常"))
if(isnull(实际时间),if(today()>计划时间,逾期,正常),if(实际时间>计划时间,逾期,正常))
if(len(b1)=0 , if(c1>a1,"逾","正") , if(b1>a1,"逾","正"))