如何查询postgres以json格式获取数据？

Question

From the table I want to select users firstname and lastname only if their age is greater than 10 in a json format.

So the output of the query should be

I could select create a json text from but not sure how to apply where clause for Key = 'AGE' and value > 10

Here is my query

select json_object_agg(key,value) from table where key in ('firstname','lastname')

Answer 1

Add an aggregate with a FILTER clause:

SELECT id,
       json_object_agg(key, value) AS json,
FROM mytable
GROUP BY id
HAVING (max(value::integer) FILTER (WHERE key = 'AGE')) > 10;