在数据库处理了，不用公式了

https://blog.csdn.net/sinat_26811377/article/details/107188400 数据库SQL方法

https://help.fanruan.com/finereport/doc-view-3802.html 帆软相对层次坐标

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上面的不好理解的话参考以下SQL（已帆软自带数据库为例）

with t as (

SELECT '2025-01-23' [日期],'北京' [省份],'0679' [编码] union ALL

SELECT '2025-01-24' [日期],'北京' [省份],'' [编码] union ALL

SELECT '2025-01-25' [日期],'北京' [省份],'' [编码] union ALL

SELECT '2025-01-26' [日期],'北京' [省份],'' [编码] union ALL

SELECT '2025-01-27' [日期],'北京' [省份],'' [编码] union ALL

SELECT '2025-01-28' [日期],'北京' [省份],'0679' [编码] union ALL

SELECT '2025-01-29' [日期],'北京' [省份],'0679' [编码] union ALL

SELECT '2025-01-30' [日期],'北京' [省份],'0678' [编码] union ALL

SELECT '2025-01-31' [日期],'北京' [省份],'' [编码]

)

SELECT T1.*,(CASE WHEN T1.编码='' OR T1.编码 IS NULL THEN (SELECT T2.编码 FROM T T2 WHERE T2.编码<>'' AND T2.日期<=T1.日期 AND T2.省份=T1.省份 order by T2.日期 desc LIMIT 1) ELSE T1.编码 END) [NEW_] FROM T T1 

可以在单元格添加条件的【新值】，如下图所示，如果是空值【len(B2)=0】并且【A2="北京市"】，新值是【0679】，如下图所示，

运行后结果如下图所示：