postgresql 字符串变json 再还原

SELECT to_json('some "text"'::text)
select array[to_json('Some "text"'::TEXT)] ;

select array_to_json(array[to_json('Some "text"'::TEXT)]) ;

select array_to_json(array[to_json('Some "text"'::TEXT)])->>0 ;

select length( array_to_json(array[to_json('Some "text"'::TEXT)])->>0 );

 

-- 神奇的postgresql json 转表 与表转josn   表中列的神奇操作
select * from json_to_record('{"a":1,"b":[1,2,3],"c":"bar"}') as x(a int, b INTEGER[], c text)
SELECT row_to_json(
  a.*
) from (select * from json_to_record('{"a":1,"b":[1,2,3],"c":"bar"}') as x(a int, b INTEGER[], c text)) a

-- 今天是第几周
SELECT EXTRACT(WEEK FROM  now());
-- 第几个月
SELECT EXTRACT(MONTH FROM now());
-- 第几个季度
SELECT EXTRACT(quarter FROM now());
-- 第几年
SELECT EXTRACT(year FROM now());