title: How to merge two IEnumerables?
body: <p>I have two Enumberable lists: list1 &amp; list2
  I want to take something from list2 and update it in list1 based on a condition</p>
  <p>e.g: list1.Id has say for instance 1, 2, 3, 4, 5 etc.
  list2.Id has 3, 4
  I need to compare these Ids and take the other fields(e.g. name, subject) from list2 which matches list1.Id (3 and 4 in this case) and copy it to list1 other fields(name, subject)</p>
  <p>list1:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>Id</th>
  <th>Name</th>
  <th>Subject</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>1</td>
  <td>N1</td>
  <td>S1</td>
  </tr>
  <tr>
  <td>2</td>
  <td>N2</td>
  <td>S2</td>
  </tr>
  <tr>
  <td>3</td>
  <td></td>
  <td></td>
  </tr>
  <tr>
  <td>4</td>
  <td></td>
  <td></td>
  </tr>
  <tr>
  <td>5</td>
  <td>N5</td>
  <td>S5</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>list2:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>Id</th>
  <th>Name</th>
  <th>Subject</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>3</td>
  <td>N3</td>
  <td>S3</td>
  </tr>
  <tr>
  <td>4</td>
  <td>N4</td>
  <td>S4</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>Required resultant:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>Id</th>
  <th>Name</th>
  <th>Subject</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>1</td>
  <td>N1</td>
  <td>S1</td>
  </tr>
  <tr>
  <td>2</td>
  <td>N2</td>
  <td>S2</td>
  </tr>
  <tr>
  <td>3</td>
  <td>N3</td>
  <td>S3</td>
  </tr>
  <tr>
  <td>4</td>
  <td>N4</td>
  <td>S4</td>
  </tr>
  <tr>
  <td>5</td>
  <td>N5</td>
  <td>S5</td>
  </tr>
  </tbody>
  </table>
  </div>