code: public function selectForPrimaryKey($primaryKeyValue, string $columns = "*"): ?array
      {
          if (is_null($this->getPrimaryKeyColumnName())) {
              throw new \Exception("$this->tableName primary key not defined");
          }
          $where = [
              $this->getPrimaryKeyColumnName() => [
                  'operators' => ['='],
                  'values' => [$primaryKeyValue],
              ],
          ];
          if (null !== $records = $this->select($columns, $where)) {
              return $records[0];
          }
          return null;
      }
docs: unlike select(), this returns only the array for a single record, or null