Power Query数据转换问题：实体条目号补全与空值填充

（图：原始数据集与预期效果对比）

我在Power Query里处理26万行的数据集转换时卡壳了（示例简化为17行），需要完成两个操作：

• 按实体扩展出所有条目号，示例中间部分是预期的完整条目样式
• 把空值向下填充，直到下一个日期出现

折腾好几个小时都没搞定，求支招。

更新内容： #

let
Source = Table.NestedJoin(#"ENTITY | DATE", {"Entity"}, #"MAX ENTRY NO", {"Entity"}, "MAX ENTRY NO", JoinKind.LeftOuter),
#"Expanded MAX ENTRY NO" = Table.ExpandTableColumn(Source, "MAX ENTRY NO", {"Max Entry No.1"}, {"Max Entry No.1"}),
#"Changed column type" = Table.TransformColumnTypes(#"Expanded MAX ENTRY NO", {{"Entity", type text}, {"Creation Date", type date}, {"From Entry No", Int64.Type}, {"Max Entry No.1", Int64.Type}})
,
#"Grouped Rows" = Table.Group(#"Changed column type", {"Entity"}, {{"From Entry No", each {List.Min([From Entry No]).. List.Max([Max Entry No.1])}}}),
#"Expanded FROM ENTRY NO" = Table.ExpandListColumn(#"Grouped Rows", "From Entry No"),
#"Merged Queries" = Table.NestedJoin(#"Expanded FROM ENTRY NO", {"Entity", "From Entry No"}, Source, {"Entity", "From Entry No"}, "Table1", JoinKind.LeftOuter),
#"Expanded Table1" = Table.ExpandTableColumn(#"Merged Queries", "Table1", {"Creation Date", "Max Entry No.1"}, {"Creation Date", "Max Entry No.1"}),
#"Sorted Rows" = Table.Sort(#"Expanded Table1",{{"Entity", Order.Ascending}, {"From Entry No", Order.Ascending}}),
#"Filled Down" = Table.FillDown(#"Sorted Rows",{"Creation Date", "Max Entry No.1"}),
#"Changed Type" = Table.TransformColumnTypes(#"Filled Down",{{"Creation Date", type date}})
in #"Changed Type"

（图：代码运行效果展示1）
（图：代码运行效果展示2）
（图：代码运行效果展示3）

内容的提问来源于stack exchange，提问作者Christopher Brogan