How to delete all rows except the first one?

[Anonymous]

Hi,

The source is a folder which contains many pdf files. All of them have only one table with at least one row of headers and some rows of data. A few files just show the table with the headers but no further content.

I only need the first row with content of each file. If there are more rows then they must be ignored.

The problem comes up at the files which have no content but only the headers as the counter of single lines goes negative.

I suppose there are far better ways to achieve my goal but yet I don't know them. Any advice would be appreciated, here's my approach:

let
    Quelle = Pdf.Tables(Parameter1, [Implementation="1.3"]),
    Table001 = Quelle{[Id="Table001"]}[Data],
    #"headers" = Table.PromoteHeaders(Table001, [PromoteAllScalars=true]),
    #"number of rows" = Table.RowCount(#"headers"),
    #"single line" = (#"number of rows")-1,
    #"result" = Table.RemoveRows(#"headers", 1, (#"single line"))
in
    #"result"

[Anonymous]

You could do your row count before promoting the headers, so your empty tables will instead have one row. Then delete the tables that have only one row, so your -1 becomes 0, and only then promote the headers. 

--Nate 

[edhans · Accepted solution]

You can count the rows with Table.RowCount, so your formula would be something like

ValidationStep = if Table.RowCount(PreviousStep) > 1 then {your filter here} else PreviousStep

So this maybe:

let
    Quelle = Pdf.Tables(Parameter1, [Implementation="1.3"]),
    Table001 = Quelle{[Id="Table001"]}[Data],
    #"headers" = Table.PromoteHeaders(Table001, [PromoteAllScalars=true]),
    #"number of rows" = Table.RowCount(#"headers"),
    #"single line" = (#"number of rows")-1,
    #"result" = if #"number of rows" > 1 then Table.RemoveRows(#"headers", 1, (#"single line")) else #"single line"
in
    #"result"