[bug] query with interval parse error

[zhyass]

create table time(a int primary key,b datetime);
insert into time(a,b) values(1, now());

mysql> select b + interval 1 day from time where a=1;
+---------------------+
| b + interval 1 day  |
+---------------------+
| 2019-09-03 15:09:19 |
+---------------------+
1 row in set (8.56 sec)

mysql> select b + INTERVAL '-1 10' DAY_HOUR from time where a=1;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '`day_hour` from zzq.time_0035 as `time` where a = 1' at line 1
mysql> explain select b + INTERVAL '-1 10' DAY_HOUR from time where a=1;
+------------------------------------------------------------------------------------------+
| EXPLAIN          
+-------------------------------------------------------------------------------------------+
| {
        "RawQuery": " select b + INTERVAL '-1 10' DAY_HOUR from time where a=1",
        "Project": "b + interval '-1 10' `day_hour`",
        "Partitions": [
                {
                        "Query": "select b + interval '-1 10' `day_hour` from zzq.time_0035 as `time` where a = 1",
                        "Backend": "backend2",
                        "Range": "[2261-2325)"
                }
        ]
} |
+------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

error log:

 2019/09/02 18:35:46.327948 connection.go:206:    	 [ERROR] 	conn[139.198.123.188:237].execute[select b + interval '-1 10' `day_hour` from zzq.time_0035 as `time` where a = 1].len[79].error:You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '`day_hour` from zzq.time_0035 as `time` where a = 1' at line 1 (errno 1064) (sqlstate 42000)
 2019/09/02 18:35:46.328031 txn.go:415:    	 [ERROR] 	txn.execute.on[139.198.123.188:237].query[select b + interval '-1 10' `day_hour` from zzq.time_0035 as `time` where a = 1].error:You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '`day_hour` from zzq.time_0035 as `time` where a = 1' at line 1 (errno 1064) (sqlstate 42000)
 2019/09/02 18:35:46.328293 query.go:240:    	 [ERROR] 	proxy.select[select b + INTERVAL '-1 10' DAY_HOUR from time where a=1].from.session[1].error:You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '`day_hour` from zzq.time_0035 as `time` where a = 1' at line 1 (errno 1064) (sqlstate 42000)
 2019/09/02 18:35:46.328325 server.go:240:    	 [ERROR] 	server.handle.query.from.session[1].error:You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '`day_hour` from zzq.time_0035 as `time` where a = 1' at line 1 (errno 1064) (sqlstate 42000).query[select b + INTERVAL '-1 10' DAY_HOUR from time where a=1]