[英]Linq query with multiple subqueries
我正在將 Oracle Sql 查詢轉換為 Linq,但不確定如何繼續。 這是 Sql 查詢:
SELECT *
FROM CustomerShip,
(SELECT DISTINCT b.ShipSeq AS shipSeq
FROM Orders a,
CustomerShip b
WHERE a.OrderId IN (SELECT OrderId
FROM Orders
WHERE CustomerId = @CustomerId
AND OrderType <> 'A')
AND b.CustomerId = @CustomerId
AND b.ShipSeq = a.CustShip
AND OrderStatus <> 'C'
GROUP BY b.ShipSeq) i
WHERE CustomerId = @CustomerId
AND (Address NOT LIKE '%RETAIL%STORE%')
AND ShipSeq = i.ShipSeq(+)
ORDER BY ShipTo DESC, OrderDate DESC;
在轉換為 linq 時,我試圖將其分解為三個單獨的查詢。
var query1 = from c in CustomerShip
where c.CustomerId == customerId
&& !c.Address.Contains("RETAIL")
&& !c.Address.Contains("STORE")
orderby c.ShipTo descending, c.OrderDate descending
select c;
var query2 = from o in Orders
where o.CustomerId == customerId
&& !o.OrderType.Equals("A")
select o.OrderId;
var query3 = (from o in Orders
from c in CustomerShip
where c.CustomerId == customerId
&& c.ShipSeq == o.CustShip
&& !o.OrderStatus.Equals("A")
select c.ShipSeq).Distinct();
現在我試圖將它們全部組合成一個查詢,但不確定如何去做。 這是我要去的方向:
var query = from c in CustomerShip
let subquery = from o in Orders
where o.CustomerId == customerId
&& !o.OrderType.Equals("A")
select o.OrderId
from or in model.Orders
where subquery.Contains(or.OrderId)
&& c.CustomerId == customerId
&& c.ShipSeq == or.CustShip
&& !or.OrderStatus.Equals("A")
group c by c.ShipSeq
into i
select c.ShipSeq
where c.CustomerId == customerId
&& !c.Address.Contains("RETAIL")
&& !c.Address.Contains("STORE")
orderby c.ShipTo descending, c.OrderDate descending
select c, i;
更新
我有一個類型有效的查詢,但它需要將近兩分鍾來執行(與 Oracle 查詢的 0.02 秒相比)並且結果的順序不正確。 有人看到我缺少什么嗎?
var innerQuery = from x in model.Orders
where x.CustomerId == customerId
&& !x.OrderType.Equals("A")
select x.OrderId;
var result = from c in model.CustomerShip
join subQuery in
(
(from o in model.Orders
from c in model.CustomerShip
where c.CustomerId == customerId
&& innerQuery.Contains(o.OrderId)
&& !o.FLAG_ORD_STATUS.Equals("C")
&& c.ShipSeq == o.CustShip
select c.ShipSeq).Distinct()
) on c.ShipSeq equals subQuery into temp
from x in temp.DefaultIfEmpty()
where c.CustomerId == customerId
&& !c.Address.Contains("RETAIL")
&& !c.Address.Contains("STORE")
orderby c.ShipTo descending, c.OrderDate descending
select c;
請記住,您只是在此處構建查詢。 在您執行ToList()
或.FirstOrDefault()
或其他任何操作之前,不會執行任何操作。 SO,您可以在其他查詢中使用這些查詢,並且在執行時會創建一個大 SQL 語句。
var query2 = from o in Orders
where o.CustomerId == customerId
&& !o.OrderType.Equals("A")
select o.OrderId;
var query3 = (from o in Orders
join c in CustomerShip on o.CustShip equals c.ShipSeq
where c.CustomerId == customerId
&& !o.OrderStatus.Equals("A")
&& query2.Contains(o.OrderId)
select c.ShipSeq).Distinct();
var query1 = from c in CustomerShip
from i in query3
where c.CustomerId == customerId
&& !c.Address.Contains("RETAIL")
&& !c.Address.Contains("STORE")
&& c.ShipSeq == i.ShipSeq
orderby c.ShipTo descending, c.OrderDate descending
select c;
但是,我很確定您可以將 query2 和 query3 減少到僅:
var query3 = (from o in Orders
join c in CustomerShip on o.CustShip equals c.ShipSeq
where c.CustomerId == customerId
&& !o.OrderStatus.Equals("A")
&& !o.OrderType.Equals("A")
select c.ShipSeq).Distinct();
嘗試這樣的事情。 我為一些類建模只是為了消除錯誤。 如果您按 ShipSeq 分組,則不需要不同。 只需從組中取出第一項就會得到相同的結果。
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
namespace ConsoleApplication60
{
class Program
{
static void Main(string[] args)
{
int customerID = 1234;
List<Order> CustomTypeA = Order.orders
.Where(x => (x.CustomerId == customerID) && (x.OrderType == "A") && (x.OrderStatus == "C")).ToList();
var results = (from CustA in CustomTypeA
join CustShip in Ship.CustomerShip on CustA.CustomerId equals CustShip.CustomerId
select new { CustA = CustA, CustShip = CustShip})
.Where(x => (!RetailStore(x.CustShip.Address)) && (x.CustA.CustShip == x.CustShip.ShipSeq))
.OrderByDescending(x => x.CustShip.OrderDate)
.GroupBy(x => x.CustShip.ShipSeq)
.Select(x => x.FirstOrDefault())
.Select(x => new {
CustomerID = x.CustShip.CustomerId,
Address = x.CustShip.Address,
OrderDate = x.CustShip.OrderDate
}).ToList();
}
static Boolean RetailStore(string address)
{
string pattern = "RETAIL.*STORE";
return Regex.IsMatch(address, pattern);
}
}
public class Order
{
public static List<Order> orders = new List<Order>();
public int CustomerId { get; set; }
public string OrderType { get; set; }
public string CustShip { get; set; }
public string OrderStatus { get; set; }
}
public class Ship
{
public static List<Ship> CustomerShip = new List<Ship>();
public int CustomerId { get; set; }
public string ShipSeq { get; set; }
public string Address { get; set; }
public DateTime OrderDate { get; set; }
}
}
query2 和 query3 在此處合並為內部查詢
var Innerquery = (from o in Orders
join c in CustomerShip on o.CustShip equals c.ShipSeq
where c.CustomerId == customerId
&& !o.OrderStatus.Equals("A")
&& !o.OrderType.Equals("A")
select c.ShipSeq).Distinct();
var query1 = from c in CustomerShip
from i in query3
where c.CustomerId == customerId
&& innerquery.Contains(c.CustomerId)
&& !c.Address.Contains("RETAIL")
&& !c.Address.Contains("STORE")
&& c.ShipSeq == i.ShipSeq
orderby c.ShipTo descending, c.OrderDate descending
select c;
或者你可以試試 Linqer http://www.sqltolinq.com
您的查詢在 EF 中變慢的原因可能有很多 - 我建議使用分析器。
可能的原因是 EF 創建了一個低效的查詢(通常數據庫應該創建它自己的優化,但我在 EF 和 Oracle 方面有過糟糕的經歷),或者,根據它加載的結果數量,將其映射到實際對象非常昂貴.
一般來說,雖然在 .NET 世界中似乎不是一個流行的觀點,但我建議創建一個視圖,或者在有復雜查詢時使用dbcontext.Database.SqlQuery<CustomerShip>(sql)
,尤其是在使用 Oracle 時,至少根據我過去的經驗(已經有一段時間了,所以我可能是錯的。)
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