# 存储的是key-value格式的数据，通过指定的key获取对应的值
# 使用->返回的结果是带引号的
select '{"nickname": "goodspeed", "avatar": "avatar_url"}'::json->'nickname' as nickname;
# 使用-返回结果不带引号
select '{"nickname": "goodspeed", "avatar": "avatar_url", "tags": ["python", "golang", "db"]}'::json-'nickname' as nickname;

# {tags,0}代表查询key=‘tags'，且value为数组中数组的第一个元素
select '{"nickname": "gs", "avatar": "avatar_url", "tags": ["python", "golang", "db"]}'::json#>'{tags,0}' as tag;
# {aa,b,0}代表查询key=‘aa'，对应的value中，key=‘b'的value中，数组的第一个元素
select '{"nickname": "gs", "avatar": "avatar_url", "tags": ["python", "golang", "db"], "aa":{"b": [{"c": 1}]}}'::jsonb#'{aa,b,0}';

jsonb_set(原数据, 需要更改的位置, 替换的值，是否不存在时新增), 
select jsonb_set('[{"f1":1,"f2":null},2,null,3]', '{0,f1}','[2,3,4]', false);