public boolean isMeasurementsExistPlaceholder() {
    for (IntoItem intoItem : intoItems) {
      if (intoItem.isMeasurementsExistPlaceholder()) {
        return true;
      }
    }
    return false;
  }
This class maintains information of {@code INTO} clause.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/statement/component/IntoComponent.java