title: Getting the last value of a column and displaying it in another column
body: <p>I am trying to get the last value of a column and display it throughout in another column. Below is a sample of the data that we have now.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>DT                             ETB_DT
  Friday 00:00:00.0000000 Friday 04:00:00.0000000
  Friday 00:00:00.0000000 Friday 08:00:00.0000000
  Friday 00:00:00.0000000 Friday 12:00:00.0000000
  Friday 00:00:00.0000000 Friday 16:00:00.0000000
  Friday 00:00:00.0000000 Friday 20:00:00.0000000
  
  No_of_records  cumulative
  22               22
  41               63
  86               149
  65               214
  25               239</code></pre>
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  <p>I am trying to get another column called total that shows the last value of cumulative throughout. Below is my desired output.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>DT                             ETB_DT
  Friday 00:00:00.0000000 Friday 04:00:00.0000000
  Friday 00:00:00.0000000 Friday 08:00:00.0000000
  Friday 00:00:00.0000000 Friday 12:00:00.0000000
  Friday 00:00:00.0000000 Friday 16:00:00.0000000
  Friday 00:00:00.0000000 Friday 20:00:00.0000000
  
  No_of_records  cumulative   total
  22               22      239
  41               63      239
  86               149     239
  65               214     239
  25               239     239</code></pre>
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  <p>Do you have any ideas? Appreciate your help.</p>