title: Add a fixed static row in a angular Mat Table
body: <p>I have a dynamic table using mat-table where i render the columns from the data object.</p>
  <pre><code> &lt;table #myTable mat-table [dataSource]=&quot;dataSource&quot; class=&quot;mat-elevation-z8&quot;&gt;...
  </code></pre>
  <p>I render the columns</p>
  <pre><code>&lt;ng-container matColumnDef=&quot;id&quot;&gt;
  &lt;th mat-header-cell *matHeaderCellDef&gt;id&lt;/th&gt;
  &lt;td mat-cell *matCellDef=&quot;let element&quot;&gt; {{element.id}} &lt;/td&gt;
  &lt;/ng-container&gt;
  ...
  
  &lt;tr mat-header-row *matHeaderRowDef=&quot;displayedColumns&quot;&gt;&lt;/tr&gt;
  &lt;tr mat-row *matRowDef=&quot;let row; columns: displayedColumns;&quot;&gt;&lt;/tr&gt;
  </code></pre>
  <p>I want to add a static row in the end of the table data where i want to show some sum values from the mat-table columns.</p>
  <p>I can provide this row name in the array like:
  private displayedColumns: string[] = ['id', 'column1', 'column2', 'column3', 'sum'];
  Where id and other column names are present in my object and mapped accordingly but how can i add this static sum row ?</p>