是否有一种“不那么丑陋”的选项可以将字符串作为 text
并将整数作为 int
?
JSON 树的所有叶子都有众所周知的数据类型,那么,如何告诉 PostgreSQL 查看数据类型?
问题的例子和丑陋的解决方案...有更少丑陋的解决方案吗?
SELECT version(); -- PostgreSQL 9.3
CREATE TABLE example (
id serial PRIMARY KEY,
info JSON
);
INSERT INTO example (info) VALUES
('{"aa":10,"bb":"nonono nononon"}'),
('{"aa":10,"x":"etc"}'),
('{"aa":9,"x":"etc etc"}');
-- SIX ERROS... But human-readable syntax
SELECT DISTINCT info->'aa' FROM example; -- ex.1
SELECT * FROM example ORDER BY info->'aa'; -- ex.2
SELECT info->'x' FROM example WHERE info->'x' IS NOT NULL; -- ex.3
SELECT * FROM example WHERE info->'x'='etc'; -- ex.4
SELECT * FROM example WHERE (info->'x')::text='etc'; -- ex.5
SELECT * FROM example WHERE info->'aa'=10; -- ex.6
-- UGLY (!!) six workarounds
SELECT DISTINCT (info->'aa')::text FROM example; -- ex.1
SELECT * FROM example ORDER BY (info->'aa')::text::int; -- ex.2
SELECT info->'x' FROM example WHERE (info->'x')::text IS NOT NULL; -- ex.3
SELECT * FROM example WHERE trim((info->'x')::text,'"')='etc'; -- exs. 4 and 5
SELECT * FROM example WHERE (info->'aa')::text::int=10; -- ex.6
最佳答案
使用->>
json operator ,它返回一个 JSON 对象字段或一个 JSON 数组作为 text
。
SELECT DISTINCT info->>'aa' FROM example;
SELECT * FROM example ORDER BY info->>'aa';
SELECT info->>'x' FROM example WHERE (info->>'x') IS NOT NULL;
SELECT * FROM example WHERE info->>'x'='etc';
SELECT * FROM example WHERE (info->>'aa')::int=10; -- still needs a cast to int
关于PostgreSQL 9.3+下的JSON,这么难看?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33986980/