add rows with missing dates to a table

[Syndicate_Admin]

Hello!

I have the following table:

and I want to get this table:

In words: in Power Query I want to intersperse rows with the missing dates/times that differ from each other with a constant value (3 hours in the example, in the real case it is every 3 minutes), for any start date and end date, and for any number of columns.

The values of the new rows must be NULL.

I describe in pseudocode of query steps a type of solution that I imagine:

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc89CoAwDIbhq5TOQtP82bq5CoJ76RXcvL9SEIo1EHinh4+U4oHCdp0BAdEBLQDPuXX3kxfSlM3W6WO1t5EF1exg392j2cSEZs3dZkV4jmYHm3ubWRnNNss/tv2bKCmbrfUG", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Fecha = _t, #"Columna 1" = _t, #"Columna 2" = _t, #"…" = _t, #"Columna n" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Fecha", type datetime}, {"Columna 1", Int64.Type}, {"Columna 2", Int64.Type}, {"…", Int64.Type}, {"Columna n", Int64.Type}}),
    #"Sorted Rows" = Table.Sort(#"Changed Type",{{"Fecha", Order.Ascending}})

tabla_temp = crear tabla con filas "desde min(columa1) hasta max(columna1) cada 3 horas" y con la misma cantidad de columnas

#"Merge" = merge con tabla_temp

in
    #"Merge"

Maybe the solution is different? I need help getting the second table from the first.

Thank you!

[lbendlin · Accepted solution]

let
    
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("dc89CoAwDIbhq5TOQtP82bq5CoJ76RXcvL9SEIo1EHinh4+U4oHCdp0BAdEBLQDPuXX3kxfSlM3W6WO1t5EF1exg392j2cSEZs3dZkV4jmYHm3ubWRnNNss/tv2bKCmbrfUG", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Fecha = _t, #"Columna 1" = _t, #"Columna 2" = _t, #"…" = _t, #"Columna n" = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Columna 1", Int64.Type}, {"Columna 2", Int64.Type}, {"…", Int64.Type}, {"Columna n", Int64.Type}}),
    #"Changed Type with Locale" = Table.TransformColumnTypes(#"Changed Type", {{"Fecha", type datetime}}, "es-MX"),
    NewTable = List.Generate(()=>List.First(#"Changed Type with Locale"[Fecha]),each _ <= List.Last(#"Changed Type with Locale"[Fecha]),each _ + #duration(0,3,0,0)),
    #"Converted to Table" = Table.FromList(NewTable, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
    #"Merged Queries" = Table.NestedJoin(#"Changed Type with Locale", {"Fecha"}, #"Converted to Table", {"Column1"}, "Merged", JoinKind.RightOuter),
    #"Expanded Merged" = Table.ExpandTableColumn(#"Merged Queries", "Merged", {"Column1"}, {"Column1"}),
    #"Changed Type1" = Table.TransformColumnTypes(#"Expanded Merged",{{"Column1", type datetime}}),
    #"Replaced Value" = Table.ReplaceValue(#"Changed Type1",null,each [Column1],Replacer.ReplaceValue,{"Fecha"}),
    #"Removed Columns" = Table.RemoveColumns(#"Replaced Value",{"Column1"}),
    #"Sorted Rows" = Table.Sort(#"Removed Columns",{{"Fecha", Order.Ascending}})
in
    #"Sorted Rows"

[Syndicate_Admin]

Thank you!! I'll learn from your code.

[Syndicate_Admin]

I just realized that I am commenting with the pescadicto user to a question from the user pescadicto_

I always used pescadicto, in my last login I had to use my organizational account and a new user was created (which I called pescadicto_ and with whom I asked the question above), in today's login the old user, pescadicto, automatically entered.

Anyway... I don't understand what's going on.

Thank you from both users!

[lbendlin]

You were already on the right track.  Generate a list of all possible timestamps and then do an outer join.  Learn about the difference between Table.SelectColumns and Table.RemoveColumns  (normally the first one is preferred but in your scenario the second one needs to be used).