postgresql - Postgresql 在查询中获取限制的记录总数

Question

我已经创建了一个表并尝试从表记录创建一个 json 数组，它将在其中返回 JSON 数组作为 {"total_record":2222,data[{row 1 data},{row 2 data}] }

下面是相同的查询

SELECT row_to_json(selected_records)::text AS data
FROM  (   
   SELECT min(total_count) AS total_count
        , array_to_json(array_agg(row_to_json(ROW(name,id,gender)))) AS data
   FROM (
      SELECT *
           , count(*) over () AS total_count  -- shouldn't show up in result
      FROM   test

      GROUP  BY ID
      LIMIT  1
      ) records
   ) selected_records;

但有些我是如何得到这样的 json 的

{"total_count":277938,"data":[{"f1":"Carol Rau","f2":1,"f3":"M"}]}

我需要列字段名而不是 f1,f2,f3

{"total_count":277938,"data":[{"name":"Carol Rau","id":1,"gender":"M"}]}

相同的 DDL:

create table public.test (name varchar, email varchar, phone bigint, address varchar, gender varchar, id serial primary key) 
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Carol Rau', 'Computers, Electronics & Games', '1000000000', 'Suite 843 489 Annabell Islands, North Katlynland, UT 90089-0425', 'M', '1');
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Vicente Sipes', 'Games', '1000000000', 'Suite 870 21754 Dare Ville, Thielstad, WA 97243-0588', 'M', '2');
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Jadyn Kris', 'Kids', '1000000000', '5136 Harmon Dale, Jeramiemouth, VT 17688', 'M', '21');
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Melyna Lueilwitz', 'Automotive, Music & Outdoors', '1000000000', 'Suite 578 0765 Paucek Meadow, Torphyborough, AR 41921', 'M', '22');
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Phoebe Herzog Sr.', 'Movies', '1000000000', '82869 Carrie Ridges, East Tavaresmouth, AR 62150', 'M', '23');
INSERT INTO "public"."test" ("name", "email", "phone", "address", "gender", "id") VALUES ('Cierra Luettgen', 'Toys', '1000000000', '326 Maida Pine, Aylamouth, IL 03742', 'M', '90');

Answer 1

已编辑

select row_to_json(t) from (
  select
    (select count(*) from public.test) as total_count,
    (select json_agg(row_to_json(tt))
       from (select name, id, gender from public.test limit 1) tt) as data
) t