POSTGRESQL - 錯誤的返回select查詢

Question

這裏是我的功能，執行此功能時，它會返回錯誤：

create or replace function country(varchar) 

returns customer(customer_id integer, 
       first_name varchar,      
        last_name varchar) as $$ 


select customer_id, customer.first_name, customer.last_name 

from customer 

    inner join address on customer.address_id = address.address_id 
    inner join city on address.city_id = city.city_id 
    inner join country on city.country_id = country.country_id 

where country = '$1'; 

$$ 
language sql; 

錯誤返回查詢發生。

Answer 1

使用創建此解決方案類型：

create type ct as (customer_id integer, first_name varchar, last_name varchar) 

現在創建功能

create or replace function country(varchar) 

returns ct as $$ 

select customer_id, first_name, last_name from customer 
    inner join address on customer.address_id = address.address_id 
    inner join city on address.city_id = city.city_id 
    inner join country on city.country_id = country.country_id  
where country = $1; 

$$ language sql; 

或使用本

create or replace function country(varchar) 

returns table(customer_id integer, 
       first_name varchar,      
        last_name varchar) as $$ 

select customer_id, customer.first_name, customer.last_name 

from customer 

    inner join address on customer.address_id = address.address_id 
    inner join city on address.city_id = city.city_id 
    inner join country on city.country_id = country.country_id 

where country = $1; 

$$language sql;