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我正在尝试使用row_to_json()PostgreSQL 9.2中添加的函数将查询结果映射到JSON .

我无法找出将连接行表示为嵌套对象的最佳方法(1:1关系)

这是我尝试过的(设置代码:表格,示例数据,然后是查询):

-- some test tables to start out with:
create table role_duties (
    id serial primary key,
    name varchar
);

create table user_roles (
    id serial primary key,
    name varchar,
    description varchar,
    duty_id int, foreign key (duty_id) references role_duties(id)
);

create table users (
    id serial primary key,
    name varchar,
    email varchar,
    user_role_id int, foreign key (user_role_id) references user_roles(id)
);

DO $$
DECLARE duty_id int;
DECLARE role_id int;
begin
insert into role_duties (name) values …