각 그룹의 최대 값 선택

각 그룹의 최대 값 선택

---

Name    Value   AnotherColumn
-----------
Pump 1  8000.0  Something1
Pump 1  10000.0 Something2
Pump 1  10000.0 Something3
Pump 2  3043    Something4
Pump 2  4594    Something5
Pump 2  6165    Something6

내 테이블은 다음과 같습니다. 각 펌프의 최대 값을 선택하는 방법을 알고 싶습니다.

select a.name, value from out_pumptable as a,
(select name, max(value) as value from out_pumptable where group by posnumber)g where and g.value = value

이 코드는 작업을 수행하지만 동일한 값을 가진 두 개의 항목이 있기 때문에 펌프 1의 두 항목을 얻습니다.

---

select name, max(value)
from out_pumptable
group by name

---

SELECT
  b.name,
  MAX(b.value) as MaxValue,
  MAX(b.Anothercolumn) as AnotherColumn
FROM out_pumptabl
INNER JOIN (SELECT 
              name,
              MAX(value) as MaxValue
            FROM out_pumptabl
            GROUP BY Name) a ON 
  a.name = b.name AND a.maxValue = b.value
GROUP BY b.Name

기본 키가 있으면 훨씬 쉬울 것입니다. 다음은 예입니다.

SELECT * FROM out_pumptabl c
WHERE PK in 
    (SELECT
      MAX(PK) as MaxPK
    FROM out_pumptabl b
    INNER JOIN (SELECT 
                  name,
                  MAX(value) as MaxValue
                FROM out_pumptabl
                GROUP BY Name) a ON 
      a.name = b.name AND a.maxValue = b.value) 

---

select name, value 
from( select name, value, ROW_NUMBER() OVER(PARTITION BY name ORDER BY value desc) as rn
from out_pumptable ) as a
where rn = 1

---

select * from (select * from table order by value desc limit 999999999) v group by v.name

---

select Name, Value, AnotherColumn
from out_pumptable
where Value =
(
  select Max(Value)
  from out_pumptable as f where f.Name=out_pumptable.Name
)
group by Name, Value, AnotherColumn

이렇게 해보세요, 작동합니다.

---

SELECT DISTINCT (t1.ProdId), t1.Quantity FROM Dummy t1 INNER JOIN
       (SELECT ProdId, MAX(Quantity) as MaxQuantity FROM Dummy GROUP BY ProdId) t2
    ON t1.ProdId = t2.ProdId
   AND t1.Quantity = t2.MaxQuantity
 ORDER BY t1.ProdId

이것은 당신에게 아이디어를 줄 것입니다.

참고 URL : https://stackoverflow.com/questions/4510185/select-max-value-of-each-group