Wählen Sie den maximalen Wert jeder Gruppe

Question

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 

Meine Tabelle sieht in etwa so aus. Ich würde gerne wissen, wie man den maximalen Wert für jede Pumpe wählt.

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 

Dieser Code erledigt den Job, aber ich bekomme zwei Einträge von Pumpe 1, da es zwei Einträge mit demselben Wert hat.

Answer 1

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 

Beachten Sie, dass dies viel einfacher wäre, wenn Sie einen Primärschlüssel hätten. Hier ist ein Beispiel

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) 

Answer 2

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

Answer 3

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 

dies wird Ihnen die Idee.

Answer 4

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