code: protected function findConstraints($table)
      {
          $sql = 'PRAGMA foreign_key_list(' . $this->quoteSimpleTableName($table->name) . ')';
          $keys = $this->db->createCommand($sql)->queryAll();
          foreach ($keys as $key) {
              $id = (int) $key['id'];
              if (!isset($table->foreignKeys[$id])) {
                  $table->foreignKeys[$id] = [$key['table'], $key['from'] => $key['to']];
              } else {
                  // composite FK
                  $table->foreignKeys[$id][$key['from']] = $key['to'];
              }
          }
      }
docs: Collects the foreign key column details for the given table.
  @param TableSchema $table the table metadata