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[英]Is this possible with LINQ-to-Entities query using Lambda Expression
[英]Using a tuple or some other complex type in a Linq-to-Entities query expression
因此,我想在客戶表中搜索所有具有相同名稱,電子郵件地址或電話號碼的所有查詢關鍵字都匹配的客戶。
...用英語比用英語更容易理解:
public IQueryable<Contact> SearchCustomers(string query)
{
var ws = from w in query.Split()
where !String.IsNullOrWhiteSpace(w)
select w;
var q =
from c in Customers
where ws.All(w =>
c.FirstName == w
|| c.LastName == w
|| c.EmailAddress == w
|| c.HomePhone == PhoneNumber.Pack(w)
|| c.CellPhone == PhoneNumber.Pack(w))
select c;
return q;
}
但是我無法在數據庫上調用PhoneNumber.Pack
,因此我需要將w
為既存儲w
的原始值又存儲Pack
ed值的格式,而我必須在客戶端執行此操作。 問題在於Linq不喜歡在表達式參數中包含元組或數組,並且不支持String.IndexOf
,因此我不能將兩個字符串合而為一,然后接受子字符串。
還有其他解決方法嗎? 還是重述查詢?
編輯:生成的SQL看起來像這樣:
SELECT
[Extent1].[ID] AS [ID],
[Extent1].[FirstName] AS [FirstName],
[Extent1].[LastName] AS [LastName],
(etc)
FROM [dbo].[Contacts] AS [Extent1]
WHERE ( NOT EXISTS (SELECT
1 AS [C1]
FROM ( SELECT 1 AS X ) AS [SingleRowTable1]
WHERE ( NOT ([Extent1].[FirstName] = N'rei' OR [Extent1].[LastName] = N'rei' OR [Extent1].[EmailAddress] = N'rei' OR [Extent1].[HomePhone] = N'rei' OR [Extent1].[CellPhone] = N'rei')) OR (CASE WHEN ([Extent1].[FirstName] = N'rei' OR [Extent1].[LastName] = N'rei' OR [Extent1].[EmailAddress] = N'rei' OR [Extent1].[HomePhone] = N'rei' OR [Extent1].[CellPhone] = N'rei') THEN cast(1 as bit) WHEN ( NOT ([Extent1].[FirstName] = N'rei' OR [Extent1].[LastName] = N'rei' OR [Extent1].[EmailAddress] = N'rei' OR [Extent1].[HomePhone] = N'rei' OR [Extent1].[CellPhone] = N'rei')) THEN cast(0 as bit) END IS NULL)
))
public IQueryable<Contact> SearchCustomers(string query)
{
var ws = from w in query.Split()
where !String.IsNullOrWhiteSpace(w)
select new { Unpacked = w , Packed = PhoneNumber.Pack(w) };
var q = Customers;
foreach(var x in ws)
{
string ux = x.Unpacked;
string px = x.Packed;
q = q.Where(
c=>
c.FirstName == ux
|| c.LastName == ux
|| c.EmailAddress == ux
|| c.HomePhone == px
|| c.CellPhone == px
);
}
return q;
}
這將產生所需的結果,並且foreach中的temp變量將解決您的問題。
我將創建一個私有結構:
private struct UnpackedAndPacked
{
public string Unpacked {get;set;}
public string Packed {get;set;}
}
var ws = from w in query.Split()
where !String.IsNullOrWhiteSpace(w)
select new UnpackedAndPacked
{
Unpacked=w,
Packed=PhoneNumber.Pack(w)
};
然后更改條件:
where ws.All(w =>
c.FirstName == w.Unpacked
|| c.LastName == w.Unpacked
|| c.EmailAddress == w.Unpacked
|| c.HomePhone == w.Packed
|| c.CellPhone == w.Packed)
select c;
我對此進行了進一步研究,我認為您不會按原樣完成此工作。 問題在於,由於ws.All
,它想為ws
序列中的每個值創建一次SQL子句集。 它需要是原始類型的序列,例如字符串。
如果您可以將代碼更改為具有兩個查詢參數,那么我認為它可能會起作用。 對於不需要打包的東西,您需要一組參數,對於需要打包的東西,則需要一組參數。 然后,您可以將其更改為LINQ方法鏈,並在兩者之間進行聯合。 以下示例。
有效。 我的代碼如下。 請注意,我使用了AdventureWorks2008R2數據庫,因此我的數據庫要比您的數據庫復雜一些-我有一組電子郵件地址和電話可以處理; 可以匹配以下任何一個:
public static IQueryable<Person> SearchCustomers(
AdventureWorksEntities entities, string nameQuery, string phoneQuery)
{
var wsu = from w in nameQuery.Split()
where !String.IsNullOrWhiteSpace(w)
select w;
var wsp = from w in phoneQuery.Split()
where !String.IsNullOrWhiteSpace(w)
select Pack(w);
return
entities.People.Where(
c => wsu.All(w => c.FirstName == w || c.LastName == w)).
Union(
entities.People.Where(
c =>
wsp.All(
w =>
c.PersonPhones.Any(p => p.PhoneNumber == w) ||
c.EmailAddresses.Any(a => a.EmailAddress1 == w))));
}
還要注意,我發現了另一種獲取跟蹤輸出的方法 :
IQueryable<Person> query = SearchCustomers(entities, "w1 w2",
"(602) (408)");
var oc = (ObjectQuery<Person>) query;
Console.WriteLine(oc.ToTraceString());
請注意, query.Where(a).Where(b)
與query.Where(a & b)
和qry.All()實質上是采用了一系列條件並將AND
語句鏈接在一起,例如(word 1 is found) && (word 2 is found) && (word 3 is found)
...
您可以使用它來執行以下操作(我正在使用擴展方法,以便可以將其鏈接到任何其他IQueryable<Customer>
的末尾)。
[System.Runtime.CompilerServices.Extension()]
public static IQueryable<Customer> Search(this IQueryable<Customer> query, string searchTerm)
{
string[] queryWords = searchTerm.Split(" ");
foreach (string w in queryWords) {
string word = w;
string packedWord = Pack(word);
query = query.Where(c => c.FirstName == word || c.LastName == word || c.HomePhone == packedWord || c.CellPhone == packedWord);
}
return query;
}
或相當於VB
<System.Runtime.CompilerServices.Extension()>
Public Function Search(query As IQueryable(Of Customer), searchTerm As String) As IQueryable(Of Customer)
Dim queryWords = searchTerm.Split(" ")
For Each w In queryWords
Dim word = w
Dim packedWord = Pack(word)
query = query.Where(Function(c) c.FirstName = word OrElse
c.LastName = word OrElse
c.HomePhone = packedWord OrElse
c.CellPhone = packedWord)
Next
Return query
End Function
我將其分為兩種方法:
在SearchCustomerPhoneNumber中,您在執行查詢之前將參數轉換為壓縮的。
由於電話號碼將不包含字母,而其他號碼將包含字母,因此可以檢查應運行哪種方法。 拆分實際上將減少數據庫的負載。
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