hive表或mysql表字段含有注释我怎么改字段名呢

Question

实在想不到好方法了，因为包含 --注释符号会让后面代码失效，
比如：alter table map_feature CHANGE 19hub??--h 19hub_avg STRING;

我这就会报错

Answer 1

mysql> show create table a;
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                      |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| a     | CREATE TABLE `a` (
  `id` int NOT NULL,
  `c1` int NOT NULL COMMENT 'this is my comment1',
  `c2` varchar(10) DEFAULT NULL COMMENT 'this is my comment2',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+-------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>
mysql> ALTER TABLE a
    -> MODIFY c1 datetime NOT NULL COMMENT 'this is my comment1_1',
    -> MODIFY c2 varchar(20) COMMENT 'this is my comment2_2';
Query OK, 0 rows affected (0.24 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> show create table a;
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                               |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| a     | CREATE TABLE `a` (
  `id` int NOT NULL,
  `c1` datetime NOT NULL COMMENT 'this is my comment1_1',
  `c2` varchar(20) DEFAULT NULL COMMENT 'this is my comment2_2',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci |
+-------+------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>