private static ApplyNode.Operator mapOperator(ComparisonExpression.Operator operator) {
    switch (operator) {
      case EQUAL:
        return ApplyNode.Operator.EQUAL;
      case NOT_EQUAL:
        return ApplyNode.Operator.NOT_EQUAL;
      case LESS_THAN:
        return ApplyNode.Operator.LESS_THAN;
      case LESS_THAN_OR_EQUAL:
        return ApplyNode.Operator.LESS_THAN_OR_EQUAL;
      case GREATER_THAN:
        return ApplyNode.Operator.GREATER_THAN;
      case GREATER_THAN_OR_EQUAL:
        return ApplyNode.Operator.GREATER_THAN_OR_EQUAL;
      case IS_DISTINCT_FROM:
      default:
        throw new IllegalArgumentException();
    }
  }
Adds a negation of the given input and remaps the provided expression to the negated expression
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/planner/SubqueryPlanner.java