code: public function findUniqueIndexes($table)
      {
          $sql = 'PRAGMA index_list(' . $this->quoteSimpleTableName($table->name) . ')';
          $indexes = $this->db->createCommand($sql)->queryAll();
          $uniqueIndexes = [];
  
          foreach ($indexes as $index) {
              $indexName = $index['name'];
              $indexInfo = $this->db->createCommand('PRAGMA index_info(' . $this->quoteValue($index['name']) . ')')->queryAll();
  
              if ($index['unique']) {
                  $uniqueIndexes[$indexName] = [];
                  foreach ($indexInfo as $row) {
                      $uniqueIndexes[$indexName][] = $row['name'];
                  }
              }
          }
  
          return $uniqueIndexes;
      }
docs: Returns all unique indexes for the given table.
  
  Each array element is of the following structure:
  
  ```php
  [
  'IndexName1' => ['col1' [, ...]],
  'IndexName2' => ['col2' [, ...]],
  ]
  ```
  
  @param TableSchema $table the table metadata
  @return array all unique indexes for the given table.