c# - 如何使用包含在 Linq to SQL 中搜索字符串

Question

我正在使用下面的代码在多列中搜索特定的字符串

IEnumerable<UserProductDetailResult> _query
    = from eml in dc.UserProductDetails
      join zk in dc.ZeekUsers on eml.aspnet_User.UserId equals zk.UserId
      where eml.aspnet_User.LoweredUserName.Equals(strUserName.ToLower())
         && (eml.Username.Contains(strSearch)
             || eml.ProductURL.Contains(strSearch)
             || eml.Nickname.Contains(strSearch))
         && !eml.IsDeleted
         && eml.IsActive
      select new UserProductDetailResult
          {
            _userProductDetail = eml,
            _zeekUser = zk
          };

其中 dc 是 DataContext 对象。

但这会返回 0 个结果。

从上面的代码生成的查询是

SELECT [t0].[UPID], [t0].[UserId], [t0].[PID], [t0].[Nickname], [t0].[Username], [t0].[ProductURL], [t0].[StartDt], [t0].[EndDt], [t0].[IsActive], [t0].[InfoData], [t0].[SocialNetworkingData], [t0].[AnalyticKey], [t0].[ProfileID], [t0].[UseDefaultAd], [t0].[UseDefaultEmail], [t0].[IsDeleted], [t0].[CreateDt], [t0].[LastUpdateDt], [t1].[ID], [t1].[UserId] AS [UserId2], [t1].[AccountType], [t1].[FirstName], [t1].[LastName], [t1].[Phone], [t1].[Address1], [t1].[Address2], [t1].[City], [t1].[State], [t1].[ZIP], [t1].[CountryID], [t1].[NickName1], [t1].[Nickname2], [t1].[AlternameEmail], [t1].[ProfileImage], [t1].[ZeekIdStatus], [t1].[RefZeekUserId], [t1].[IsActive] AS [IsActive2], [t1].[FailureCount], [t1].[IsBlocked], [t1].[IsFirstVisit], [t1].[IsWizardPassed], [t1].[IPAddress], [t1].[TimeZoneID], [t1].[CreateDt] AS [CreateDt2], [t1].[LastUpdateDt] AS [LastUpdateDt2]
FROM [dbo].[UserProductDetails] AS [t0]
INNER JOIN [dbo].[ZeekUsers] AS [t1] ON ((
    SELECT [t2].[UserId]
    FROM [dbo].[aspnet_Users] AS [t2]
    WHERE [t2].[UserId] = [t0].[UserId]
    )) = [t1].[UserId]
INNER JOIN [dbo].[aspnet_Users] AS [t3] ON [t3].[UserId] = [t0].[UserId]
WHERE ([t3].[LoweredUserName] = 'username') AND (([t0].[Username] LIKE 'a') OR ([t0].[ProductURL] LIKE 'a') OR ([t0].[Nickname] like 'a')) AND (NOT ([t0].[IsDeleted] = 1)) AND ([t0].[IsActive] = 1)

一旦删除下面的搜索行，它就会工作并返回，

&& (eml.Username.Contains(strSearch)
    || eml.ProductURL.Contains(strSearch)
    || eml.Nickname.Contains(strSearch))

但这不允许我搜索

谁能告诉我应该如何进行？

Answer 1

根据您生成的查询，我认为您正在使用 linq-to-sql。你可以使用 SqlMethods.Like从 MSDN 生成正确的 like 查询运算符:

Determines whether a specific character string matches a specified pattern. This method is currently only supported in LINQ to SQL queries.

示例:

// first sample, any part of string
strSearch = string.Format("%[^a-zA-Z]{0}[^a-zA-Z]%", strSearch);

// on the end of the string
strSearch = string.Format("%[^a-zA-Z]{0}", strSearch);

//on the begining of the string
strSearch = string.Format("{0}[^a-zA-Z]%", strSearch);

在你的查询语句中..

(SqlMethods.Like(eml.Username, strSearch) 
|| SqlMethods.Like(eml.ProductURL, strSearch) 
|| SqlMethods.Like(eml.Nickname, strSearch))

否则，您可以在查询前的 strSearch 字符串中添加 % 字符，以生成包含字符串任何部分信息的查询，例如:

strSearch = string.Contat("%", strSearch, "%");