用于在多个列中预加前值的m代码

let
    // 步骤1：导入数据
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUQrV0lFyUlBqSVFYBAA=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t, Column3 = _t]),

    // 步骤2：添加前一个值列
    AddPreviousValue = Table.AddColumn(Source, "PreviousValue", each null),

    // 步骤3：计算前一个值
    CalculatePreviousValue = Table.FromColumns(Table.ToColumns(AddPreviousValue) & {List.Accumulate({1..Table.ColumnCount(AddPreviousValue)}, {}, (state, current) => state & {List.Last(state) & AddPreviousValue{current}[Column1]}))}),

    // 步骤4：删除原始列
    RemoveOriginalColumns = Table.RemoveColumns(CalculatePreviousValue, {"Column1", "Column2", "Column3"}),

    // 步骤5：重命名列
    RenameColumns = Table.RenameColumns(RemoveOriginalColumns, {"Column1.1", "Column1", "Column2.1", "Column2", "Column3.1", "Column3"})
in
    RenameColumns