MySQL使用日期列作为UNIQUE索引

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_extract

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_date-format

https://dev.mysql.com/doc/refman/8.0/en/create-table-generated-columns.html

https://dev.mysql.com/doc/refman/8.0/en/date-and-time-functions.html#function_get-format

只能使用自动生成列，将DATETIME类型转为VARCHAR类型，然后根据 column(length) 进行加索引，可根据一定的时间规则防止用户重复点击

无法使用DATETIME类型指定长度的情况下进行加索引，所以只能转为varchar类型

`gen_create_datetime` varchar(14) CHARACTER SET utf8 COLLATE utf8_bin GENERATED ALWAYS AS (date_format(`create_time`,get_format(DATETIME, _utf8mb4'INTERNAL'))) STORED 

UNIQUE KEY `organ_id` (`organ_id`,`gen_create_datetime`(12),`del_flag`) USING BTREE