Google Spreadsheet adding sheetname - google-sheets

Question

I have my current query below;
=QUERY({Source_1!B2:I;Source_2!B2:I;Source_3!B2:I},"select * where Col3 is not null",0)
I want to have all my data be combine to one to "All_Sheet" tab it works so far.
Now I need in Col A of my tab "All_Sheet" be included to all rows the Sheet Name like Source_1, Source_2 and so on.

Answer 1

Try this:
Add a calculated column
First build a range that contains the sheet name you want to reference. I did it by concatenating a range that is empty and the sheet name:
{N2:N&"Sheet1",Source_1!B2:I}
The above by itself won't work, because it needs to be told that it is an array. So we wrap it in ARRAYFORMULA():
ARRAYFORMULA({N2:N&"Sheet1",Source_1!B2:I})
Which gives a range that looks like this:
Then build up the rest of your query like this:
Sheet 1 | B2 Value | C2 Value | D2 Value | ...
Build our Query
Take the above and build up your multiple ranges and complete your query. Linebreaks for readability
=QUERY(
ARRAYFORMULA(
{
N2:N&"Sheet1",Source_1!B2:I;
N2:N&"Sheet2",Source_2!B2:I;
N2:N&"Sheet3", Source_3!B2:I
}),
"select * where Col3 is not null",0)