fn_Calendar.pq

let CreateDateTable = (StartDate as date, EndDate as date, optional Culture as nullable text) as table =>
  let
    // Determine number of days between start and end date
    DayCount = Duration.Days(Duration.From(EndDate - StartDate)),
    // Add a day back, as Duration math above will give you the days literally between rather than inclusive. Ex Dec 31 - Dec 1 = 30 days, but we need 31 days in that period
    DayCountAdd = DayCount + 1,
    // Create a Dates list object starting at the start date, for the duration of the day count, increment of one year
    Source = List.Dates(StartDate,DayCountAdd,#duration(1,0,0,0)),
    // Turn that date list into a table
    TableFromList = Table.FromList(Source, Splitter.SplitByNothing()),    
    // Update the type to Date
    ChangedType = Table.TransformColumnTypes(TableFromList,{{"Column1", type date}}),
    // Rename the only column in the table to date
    RenamedColumns = Table.RenameColumns(ChangedType,{{"Column1", "Date"}}),
    // Insert columns for different units within the date dimension and supporting columns for sorting
    // Optional Culture parameter is used where applicable
    InsertYear = Table.AddColumn(RenamedColumns, "Year", each Date.Year([Date])),
    InsertQuarter = Table.AddColumn(InsertYear, "QuarterNumber", each Date.QuarterOfYear([Date])),
    InsertMonth = Table.AddColumn(InsertQuarter, "MonthNumber", each Date.Month([Date])),
    InsertDay = Table.AddColumn(InsertMonth, "DayOfMonth", each Date.Day([Date])),
    InsertDayInt = Table.AddColumn(InsertDay, "DateInt", each [Year] * 10000 + [MonthNumber] * 100 + [DayOfMonth]),
    InsertMonthName = Table.AddColumn(InsertDayInt, "Month", each Date.ToText([Date], "MMMM", Culture), type text),
    InsertCalendarMonth = Table.AddColumn(InsertMonthName, "Month Of Year", each (try(Text.Range([Month],0,3)) otherwise [Month]) & " " & Number.ToText([Year])),
    InsertCalendarQtr = Table.AddColumn(InsertCalendarMonth, "Quarter of Year", each "Q" & Number.ToText([QuarterNumber]) & " " & Number.ToText([Year])),
    InsertDayWeek = Table.AddColumn(InsertCalendarQtr, "DayInWeek", each Date.DayOfWeek([Date])),
    InsertDayName = Table.AddColumn(InsertDayWeek, "Day Of Week Name", each Date.ToText([Date], "dddd", Culture), type text),
    InsertWeekStarting = Table.AddColumn(InsertDayName, "Week Starting", each Date.StartOfWeek([Date]), type date),
    InsertWeekEnding = Table.AddColumn(InsertWeekStarting, "Week Ending", each Date.EndOfWeek([Date]), type date),
    InsertMonthYrSort = Table.AddColumn(InsertWeekEnding, "MonthYrSort", each Date.ToText([Date], "yyyyMM", Culture), type number),
    InsertQuarterSort = Table.AddColumn(InsertMonthYrSort, "QuarterYrSort", each Number.ToText([Year]) & Number.ToText([QuarterNumber])),
    ChangeTypes2 = Table.TransformColumnTypes(InsertQuarterSort, {{"MonthYrSort", type number},{"QuarterYrSort", type number}}),
    InsertWeekOfYr = Table.AddColumn(ChangeTypes2, "Week", each "W" & Number.ToText(Date.WeekOfYear([Date])), type text)
  in
    InsertWeekOfYr
in
    CreateDateTable

My go-to Date table function