title: SQL: how to remove duplicate rows when value in Column 1 = value in Column 2 and vice versa
body: <p>I have a table like this:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>column_1</th>
  <th>column_2</th>
  <th>column_3</th>
  <th>column_4</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>41d97f0c-7c0b-441b-b947-d18ad2778899</td>
  <td>1feb623f-781f-4c0e-9230-861970bd2e91</td>
  <td>random1</td>
  <td>2022-01-01</td>
  </tr>
  <tr>
  <td>1feb623f-781f-4c0e-9230-861970bd2e91</td>
  <td>41d97f0c-7c0b-441b-b947-d18ad2778899</td>
  <td>random2</td>
  <td>2022-01-01</td>
  </tr>
  <tr>
  <td>7c1cbb7b-fefc-4ab8-827d-4e1a9a130da9</td>
  <td>4722b35b-7ebb-4bb7-bd84-bd290fba5d3e</td>
  <td>random3</td>
  <td>2022-01-02</td>
  </tr>
  <tr>
  <td>1313a680-5f87-4c03-b8a0-4c5743f0f2a4</td>
  <td>da67bcae-dad5-4122-95a2-7f6c32ca85e7</td>
  <td>random4</td>
  <td>2022-01-03</td>
  </tr>
  <tr>
  <td>da67bcae-dad5-4122-95a2-7f6c32ca85e7</td>
  <td>1313a680-5f87-4c03-b8a0-4c5743f0f2a4</td>
  <td>random5</td>
  <td>2022-01-04</td>
  </tr>
  </tbody>
  </table>
  </div>
  <p>For all rows where column_1 == column_2 and column_2 == column_1, I want to remove one of them as its a duplicate. In above example first 2 rows are duplicates, so I want to ignore 2nd row. Last 2 rows are also duplicates so I want to remove last row. The end result should look like:</p>
  <div class="s-table-container">
  <table class="s-table">
  <thead>
  <tr>
  <th>column_1</th>
  <th>column_2</th>
  <th>column_3</th>
  <th>column_4</th>
  </tr>
  </thead>
  <tbody>
  <tr>
  <td>41d97f0c-7c0b-441b-b947-d18ad2778899</td>
  <td>1feb623f-781f-4c0e-9230-861970bd2e91</td>
  <td>random1</td>
  <td>2022-01-01</td>
  </tr>
  <tr>
  <td>7c1cbb7b-fefc-4ab8-827d-4e1a9a130da9</td>
  <td>4722b35b-7ebb-4bb7-bd84-bd290fba5d3e</td>
  <td>random3</td>
  <td>2022-01-02</td>
  </tr>
  <tr>
  <td>1313a680-5f87-4c03-b8a0-4c5743f0f2a4</td>
  <td>da67bcae-dad5-4122-95a2-7f6c32ca85e7</td>
  <td>random4</td>
  <td>2022-01-03</td>
  </tr>
  </tbody>
  </table>
  </div>