여러 열에서 중복 항목을 찾으려면 어떻게합니까?

여러 열에서 중복 항목을 찾으려면 어떻게합니까?

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그래서 아래의 SQL 코드와 같은 작업을하고 싶습니다.

select s.id, s.name,s.city 
from stuff s
group by s.name having count(where city and name are identical) > 1

다음을 생성하려면 (그러나 이름 만 또는 도시 만 일치하는 경우 무시하고 두 열 모두에 있어야 함) :

id      name  city   
904834  jim   London  
904835  jim   London  
90145   Fred  Paris   
90132   Fred  Paris
90133   Fred  Paris

---

id쌍에 대해 복제 됨 name및 city:

select s.id, t.* 
from [stuff] s
join (
    select name, city, count(*) as qty
    from [stuff]
    group by name, city
    having count(*) > 1
) t on s.name = t.name and s.city = t.city

---

 SELECT name, city, count(*) as qty 
 FROM stuff 
 GROUP BY name, city HAVING count(*)> 1

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이와 같은 것이 트릭을 할 것입니다. 성능에 대해 모르기 때문에 몇 가지 테스트를 수행하십시오.

select
  id, name, city
from
  [stuff] s
where
1 < (select count(*) from [stuff] i where i.city = s.city and i.name = s.name)

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를 사용하면 count(*) over(partition by...)원치 않는 반복을 찾을 수있는 간단하고 효율적인 방법을 제공하는 동시에 영향을받는 모든 행과 원하는 열을 모두 나열합니다.

SELECT
    t.*
FROM (
    SELECT
        s.*
      , COUNT(*) OVER (PARTITION BY s.name, s.city) AS qty
    FROM stuff s
    ) t
WHERE t.qty > 1
ORDER BY t.name, t.city

최신 RDBMS 버전은 count(*) over(partition by...) MySQL V 8.0을 지원하지만 아래와 같이 "창 기능"을 도입했습니다 (MySQL 8.0).

CREATE TABLE stuff(
   id   INTEGER  NOT NULL
  ,name VARCHAR(60) NOT NULL
  ,city VARCHAR(60) NOT NULL
);

INSERT INTO stuff(id,name,city) VALUES 
  (904834,'jim','London')
, (904835,'jim','London')
, (90145,'Fred','Paris')
, (90132,'Fred','Paris')
, (90133,'Fred','Paris')

, (923457,'Barney','New York') # not expected in result
;

SELECT
    t.*
FROM (
    SELECT
        s.*
      , COUNT(*) OVER (PARTITION BY s.name, s.city) AS qty
    FROM stuff s
    ) t
WHERE t.qty > 1
ORDER BY t.name, t.city

    아이디 | 이름 | 도시 | 수량
----- : | : --- | : ----- | -:
 90145 | 프레드 | 파리 | 삼
 90132 | 프레드 | 파리 | 삼
 90133 | 프레드 | 파리 | 삼
904834 | 짐 | 런던 | 2
904835 | jim  | London |   2

db<>fiddle here

Window functions. MySQL now supports window functions that, for each row from a query, perform a calculation using rows related to that row. These include functions such as RANK(), LAG(), and NTILE(). In addition, several existing aggregate functions now can be used as window functions; for example, SUM() and AVG(). For more information, see Section 12.21, “Window Functions”.

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You have to self join stuff and match name and city. Then group by count.

select 
   s.id, s.name, s.city 
from stuff s join stuff p ON (
   s.name = p.city OR s.city = p.name
)
group by s.name having count(s.name) > 1

---

A little late to the game on this post, but I found this way to be pretty flexible / efficient

select 
    s1.id
    ,s1.name
    ,s1.city 
from 
    stuff s1
    ,stuff s2
Where
    s1.id <> s2.id
    and s1.name = s2.name
    and s1.city = s2.city

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Given a staging table with 70 columns and only 4 representing duplicates, this code will return the offending columns:

SELECT 
    COUNT(*)
    ,LTRIM(RTRIM(S.TransactionDate)) 
    ,LTRIM(RTRIM(S.TransactionTime))
    ,LTRIM(RTRIM(S.TransactionTicketNumber)) 
    ,LTRIM(RTRIM(GrossCost)) 
FROM Staging.dbo.Stage S
GROUP BY 
    LTRIM(RTRIM(S.TransactionDate)) 
    ,LTRIM(RTRIM(S.TransactionTime))
    ,LTRIM(RTRIM(S.TransactionTicketNumber)) 
    ,LTRIM(RTRIM(GrossCost)) 
HAVING COUNT(*) > 1

.

참고URL : https://stackoverflow.com/questions/8149210/how-do-i-find-duplicates-across-multiple-columns