[英]Linq Group By & Sum Query On Multiple Columns
var fpslist = db.FPSinformations.Where(x => x.Godown_Code != null && x.Godown_Code == godownid).ToList();
var data1 = fpslist.GroupBy(x => x.Ration_Card_Type1)
.Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count1)
}).ToList();
var data2 = fpslist.GroupBy(x => x.Ration_Card_Type2)
.Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count2)
}).ToList();
var data3 = fpslist.GroupBy(x => x.Ration_Card_Type3)
.Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count3)
}).ToList();
var data4 = fpslist.GroupBy(x => x.Ration_Card_Type4)
.Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count4)
}).ToList();
var data5 = fpslist.GroupBy(x => x.Ration_Card_Type5)
.Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count5)
}).ToList();
var GodownRCCount = data1.Where(x => x.CardType_Name != null).ToList();
var GodownRCCounts = GodownRCCount;
GodownRCCount = data2.Where(x => x.CardType_Name != null).ToList();
GodownRCCounts.AddRange(GodownRCCount);
GodownRCCount = data3.Where(x => x.CardType_Name != null).ToList();
GodownRCCounts.AddRange(GodownRCCount);
GodownRCCount = data4.Where(x => x.CardType_Name != null).ToList();
GodownRCCounts.AddRange(GodownRCCount);
GodownRCCount = data5.Where(x => x.CardType_Name != null).ToList();
GodownRCCounts.AddRange(GodownRCCount);
我的数据库中有10列
Ration_Card_Type1
Ration_card_count1
Ration_Card_Type2
Ration_card_count2
Ration_Card_Type3
Ration_card_count3
Ration_Card_Type4
Ration_card_count4
Ration_Card_Type5
Ration_card_count5
现在我要从类型中获取Ration_Card_Counts及其类型的总和
预期产量:
CardType_Name
CardType_Count
上面的代码很好用,但是我想以最大可能的方式对其进行优化,因为这将在一个循环中,并且大约有150万条记录。
谢谢
您可以使用SQL重写同一查询,并放置一些索引(性能):
SELECT Ration_Card_Type = Ration_Card_Type1, Ration_Card_Count = sum(Ration_card_count1)
FROM
FPSinformations
GROUP BY
Ration_Card_Type1
UNION
SELECT Ration_Card_Type = Ration_Card_Type2, Ration_Card_Count = sum(Ration_card_count2)
FROM
FPSinformations
GROUP BY
Ration_Card_Type2
UNION
SELECT Ration_Card_Type = Ration_Card_Type3, Ration_Card_Count = sum(Ration_card_count3)
FROM
FPSinformations
GROUP BY
Ration_Card_Type3
UNION
SELECT Ration_Card_Type = Ration_Card_Type4, Ration_Card_Count = sum(Ration_card_count4)
FROM
FPSinformations
GROUP BY
Ration_Card_Type4
UNION
SELECT Ration_Card_Type = Ration_Card_Type5, Ration_Card_Count = sum(Ration_card_count5)
FROM
FPSinformations
GROUP BY
Ration_Card_Type5
我不确定,但是这个查询使我想到了UNPIVOT,也许您也可以朝这个方向进行调查。
Union的运行速度应比AddRange快! 您可以尝试以下操作:
var data = (from g in fpslist.GroupBy(x => x.Ration_Card_Type1).Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count1)
}).Union(
fpslist.GroupBy(x => x.Ration_Card_Type2).Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count2)
})).Union(
fpslist.GroupBy(x => x.Ration_Card_Type3).Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count3)
})).Union(
fpslist.GroupBy(x => x.Ration_Card_Type4).Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count4)
})).Union(
fpslist.GroupBy(x => x.Ration_Card_Type5).Select(x => new
{
CardType_Name = x.Key,
CardType_Count = x.Sum(y => y.Ration_Card_Count5)
}))
select g).ToList();
一般来说,从分组的角度来看,我会和托马斯一起去! 数据库分组对我来说要好得多,因为您正在获取需要聚合的数据,因此,通过网络传输的数据要少得多!
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