title: Null data table
body: <p>I have the following data.table (data6):</p>
  
  <pre><code>&gt; head (data6)
     sequenceID transactionID eventID
  1:   36652675          2862       1
  2:   38763251            68       1
  3:   39535156        113964       1
  4:   39535156        113965       2
  5:   39535156        113966       3
  6:   39535156        113967       4
                                                                                                               items
  1:                                                                         34D89F927092290A5DA9B108F7020C19 SELECT
  2:                                           15873DB37BF80750C70B68A8778B9DC01D548B6D06E3BF92CADAFF289B3FCAEE CALL
  3:                                                                         005C9FFB9292EDFF0356C4326B14CA06 SELECT
  4:                                           9AD4E96D7EF2FC7B64407EAF4E2274868B2C0545BFBA9F15F828D9986D484A4D CALL
  5: 828F0D137BDA57F7F4F02801B0E51FDEDCB610BC734FE31D26399E5CBCE651FF SELECT;5BD81A7A48EDA2B8E56100CE844D3BE7 SELECT
  6: 828F0D137BDA57F7F4F02801B0E51FDEDCB610BC734FE31D26399E5CBCE651FF SELECT;5BD81A7A48EDA2B8E56100CE844D3BE7 SELECT
  </code></pre>
  
  <p>I use the following command:</p>
  
  <pre><code>data6&lt;-setDT(data6)[,if(any(eventID&gt;2)) .SD , sequenceID][,names(data),with=FALSE] 
  </code></pre>
  
  <p>And I get as a result: </p>
  
  <pre><code>&gt; data6
  Null data.table (0 rows and 0 cols)
  </code></pre>
  
  <p>Why is it?</p>