sql - StartsWith() 在 LINQ 中不会转换为 Like ('abc%' )

Question

我有以下 asp.net 核心 LINQ 代码:

    List<UserSearchResult> results = await db.ApplicationUsers.Where(u => u.Name.StartsWith(name) && !u.Deleted && u.AppearInSearch)
                                    .OrderByDescending(u => u.Verified)
                                    .ThenBy(u => u.DateAdded) // Added to prevent duplication of results in different pages
                                    .Skip(page * recordsInPage)
                                    .Take(recordsInPage)
                                    .Select(u => new UserSearchResult()
                                    {
                                        Name = u.Name,
                                        Verified = u.Verified,
                                        PhotoURL = u.PhotoURL,
                                        UserID = u.Id,
                                        Subdomain = u.Subdomain
                                    }).ToListAsync();

不幸的是，这转化为以下内容:

SELECT [t].[Name], [t].[Verified], [t].[PhotoURL], [t].[Id], [t].[Subdomain]  FROM (      SELECT [u0].*      FROM [AspNetUsers] AS [u0]      WHERE ((([u0].[Name] LIKE @__name_0 + N'%' AND (CHARINDEX(@__name_0, [u0].[Name]) = 1)) OR (@__name_0 = N'')) AND ([u0].[Deleted] = 0)) AND ([u0].[AppearInSearch] = 1)      ORDER BY [u0].[Verified] DESC, [u0].[DateAdded]      OFFSET @__p_1 ROWS FETCH NEXT @__p_2 ROWS ONLY  ) AS [t]

我想知道为什么它有这个部分:

(CHARINDEX(@__name_0, [u0].[Name]) = 1)) OR (@__name_0 = N''))

不仅喜欢

非常感谢

Answer 1

Entity Framework 提供特殊函数 EF.Functions.Like 以将其用于具有标准 SQL LIKE 语法的 LINQ 表达式。对于 StartWith 模式，表达式将如下所示:

var likeExpression = name+"%";
... await db.ApplicationUsers.Where(u => EF.Functions.Like(u.Name,likeExpression)...