public static boolean isQualifiedAllFieldsReference(Expression expression) {
    return expression instanceof DereferenceExpression
        && ((DereferenceExpression) expression).field == null;
  }
If this DereferenceExpression looks like a QualifiedName, return QualifiedName. Otherwise
return null
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/relational/sql/ast/DereferenceExpression.java