public String getSqlDialect() {
    if (connection != null && StringUtils.isNotBlank(connection.getSqlDialect())) {
      return connection.getSqlDialect().toLowerCase();
    } else {
      return "tree";
    }
  }
There are two kinds of sql here: (1) query sql (2) update sql.

<p>(1) return IoTDBJDBCResultSet or IoTDBNonAlignJDBCResultSet (2) simply get executed
iotdb-client/jdbc/src/main/java/org/apache/iotdb/jdbc/IoTDBStatement.java