需求：

1、当报表期间是1月时，取上年12月报表的期末数

2、当报表期间不是1月时，取上月报表的期末数

公式设置如下：

IF(RIGHT(rptDate("YYYY年M月"),3)="年1月",csRef("","","GROUPCOMMREPORT","个别报表模板编码",-1,12,"表页名称","单元格名称","","",TRUE,"",""),csRef("","","GROUPCOMMREPORT","个别报表模板编码",0,-1,"表页名称","单元格名称","","",TRUE,"",""))