1.修改表:ALTER TABLE table_name SET TBLPROPERTIES('comment' = '这是表注释!');
2.修改字段:
ALTER TABLE table_name CHANGE COLUMN muid muid_new STRING COMMENT '这里是列注释!';
3.json字段解析(get_json_object)
select
date,
url,
get_json_object(`extract_json`, '$.text') as `text`,
get_json_object( get_json_object(`extract_json`, '$.status'),'$.play_count') as `play_count`,
get_json_object(`extract_json`, '$.id') as `id`
from
default.vertical_crawler_result_daily
where
date = '20171201'and seed_id = 132