private String parseAlias(IoTDBSqlParser.AliasContext ctx) {
    String alias;
    if (ctx.constant() != null) {
      alias = parseConstant(ctx.constant());
    } else {
      alias = parseIdentifier(ctx.identifier().getText());
    }
    return alias;
  }
Function for parsing Alias of ResultColumn.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/parser/ASTVisitor.java