Add new row as datetime using Power Query

Hi Anonymous ，

Not quite sure what you are looking for. Do you want to add a column with a specific date for each row or add multiple rows with a specific date? Could you please provide some raw example data and the final table data you want? I have created a sample file(see attachment) for you, please check if it is the result you want...

Situation 1. Insert rows

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("ddBLCsAgDATQqxTXgmbyUXsV8f7XaKkRulDIbt5iJr0HkmLCOcRASJCEDLrAt7b3wohLkAs9Criwo2AX5SjERd0KNsXq0bYCrVqZgvNWiJbqa5m2Qg3zH+nL8cvHAw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [codunidade = _t, date = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"codunidade", Int64.Type}, {"date", type datetime}}),
    #"Filtered Rows" = Table.SelectRows(#"Changed Type", each [date] = #datetime(2021, 12, 31, 23, 59, 59)),
    #"New Rows" = Table.InsertRows(#"Filtered Rows",Table.RowCount(#"Filtered Rows"),{[codunidade = 1435883, date = DateTime.FromText("2021-12-31T23:59:59")] , [codunidade = 918465, date = DateTime.FromText("2021-12-31T23:59:59")] , [codunidade = 1435885, date = DateTime.FromText("2021-12-31T23:59:59")]})
in
    #"New Rows"

Situation 2. add date column

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Tc7JDQAhDAPAXvLmkYsctSD6b2PJCqR8R7bltYDUTQVhQBjs8YAOEGITPpLRQA44NdAayQtik2sk5QJnmFfiVXR6YIdp/B+pyv4A", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [codunidade = _t, Sales = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"codunidade", Int64.Type}, {"Sales", Int64.Type}}),
    #"Filtered Rows" = Table.SelectRows(#"Changed Type", each [Sales] >= 90),
    #"Added Custom" = Table.AddColumn(#"Filtered Rows", "Custom", each DateTime.FromText("2021-12-31T23:59:59"))
in
    #"Added Custom"

Best Regards