Add row with previous month of min month date in load script

[Madina]

Hello,

I have a table like below

sea:

LOAD
Date(data , 'DD.MM.YYYY') AS data ,

id,

name

FROM [lib://qwerty/file.xlsx]
(ooxml, embedded labels, table is Seas);

What I want is to add empty row to this table, with only date written in data. And what is needed is to write date on one month less that in original table. 

For example, if in original table sea, my minimum date is  01.01.2020 , I want to add row where date will be 01.12.2019. And other columns in that row is just empty

I tried to have a variable 

let mindate = Num(MakeDate(Year(Min(dateid)), Month(Min(dateid)), 1));

And just add month less from that to other table and concatenate, but dont know how to get previous month

Thanks in advance

[Ahidhar]

try something like this , you can autogenerate as many as you want

tab:
load * Inline
[
date,id
01/5/2020,1
01/4/2020,2
01/3/2020,3
01/2/2020,4
01/1/2020,5
];

let mindate=num(peek('date',-1,'tab'));
join(tab)
tab1:
load
date(AddMonths($(mindate),-RowNo()),'DD/MM/YYYY') as date
AutoGenerate 100;

[anat]

sea:

LOAD
Date(data , 'DD.MM.YYYY') AS data ,

id,

name

FROM [lib://qwerty/file.xlsx]
(ooxml, embedded labels, table is Seas);

concatenate(sea)

LOAD
Date(addmonths(data,-1) , 'DD.MM.YYYY') AS data ,

'' as id,

'' as name

resident sea;