PostgresSQL에서 Count를 기준으로 사용하는 방법

Question

"account", "tax_year"및 기타 필드가있는 기존 table1이 있습니다. CONCAT (account, tax_year)의 빈도가 1이고 WHERE 절을 만날 때 table1의 레코드로 table2를 작성하려고합니다. 예를 들어

이 표는 다음과 같다 경우 :

account year 
aaa 2014 
bbb 2016 
bbb 2016 
ddd 2014 
ddd 2014 
ddd 2015 

표 2는해야한다 : 나는 이틀에 보냈다

DROP TABLE IF EXISTS table1; 
CREATE table2 AS 
SELECT 
    account::text, 
    tax_year::text, 
    building_number, 
    imprv_type, 
    building_style_code, 
    quality, 
    quality_description, 
    date_erected, 
    yr_remodel, 
    actual_area, 
    heat_area, 
    gross_area, 
    CONCAT(account, tax_year) AS unq 
FROM table1 
WHERE imprv_type=1001 and date_erected>0 and date_erected IS NOT NULL and quality IS NOT NULL and quality_description IS NOT NULL and yr_remodel>0 and yr_remodel IS NOT NULL and heat_area>0 and heat_area IS NOT NULL 
GROUP BY account, 
    tax_year, 
    building_number, 
    imprv_type, 
    building_style_code, 
    quality, 
    quality_description, 
    date_erected, 
    yr_remodel, 
    actual_area, 
    heat_area, 
    gross_area, 
    unq 
HAVING COUNT(unq)=1; 

: 여기

account year 
aaa 2014 
ddd 2015 

내 스크립트입니다 하지만 여전히 올바른 방법을 찾아 낼 수는 없습니다. 도와 주셔서 감사합니다!

Answer 1

table1에 쌍 (account, tax_year)의 수를 사용하는 적절한 방법 :

select account, tax_year 
from table1 
where imprv_type=1001 -- and many more... 
group by account, tax_year 
having count(*) = 1; 

그래서 당신이 시도해야는 :

create table table2 as 
select * 
from table1 
where (account, tax_year) in (
    select account, tax_year 
    from table1 
    where imprv_type=1001 -- and many more... 
    group by account, tax_year 
    having count(*) = 1 
    ); 

Answer 2

COUNT() = 1는 NOT EXISTS(another with the same key fields) 동등하다 :

SELECT 
    account, tax_year 
    -- ... maybe more fields ... 
FROM table1 t1 
WHERE NOT EXISTS (SELECT * 
    FROM table1 nx 
    WHERE nx.account = t1.account -- same key field(s) 
    AND nx.tax_year = t1.tax_year 
    AND nx.ctid <> t1.ctid   -- but a different row! 
    ); 

참고 : I 복합 검색 키가 키 필드의 COUNT(CONCAT(account, tax_year) 연결을 대체.