使用实体框架(核心)在Linq中进入组后左连接
hid*_*den 6 linq entity-framework
问题:我想使用linq语法(实体框架7)在所需的输出中生成下面的确切sql
问题的目标是生成下面的确切sql! 期望的输出
select a.AppUserId, u.Email, a.FirstName, a.MiddleName, a.LastName, a.IsInternal, a.AspNetUserId, a.PictureLink, a.SignatureLink, a.PhoneNumber, a.Extension, a.FaxNumber, a.MobileNumber, a.Skype, r.Name as 'Role', a.SupervisorId, a.BackUpId, a.HasAutoAssignClaims, a.IsActive
from AppUser a
join AspNetUsers u on a.AspNetUserId = u.Id
left join AspNetUserRoles ur on u.Id = ur.UserId
left join AspNetRoles r on ur.RoleId = r.Id
我只能得到完全相同的sql但内部连接.我似乎无法得到两个左连接.这里的代码如何生成内部联接以及生成左联接的失败尝试.
SELECT [a].[AppUserId], [a].[FirstName], [a].[MiddleName], [a].[LastName], [a].[IsInternal], [a].[AspNetUserId], [a].[PictureLink], [a].[SignatureLink], [a].[PhoneNumber], [a].[Extension], [a].[FaxNumber], [a].[MobileNumber], [a].[Skype], [a].[SupervisorId], [a].[BackUpId], [a].[HasAutoAssignClaims], [a].[IsActive]
FROM [AppUser] AS [a]
INNER JOIN [AspNetUsers] AS [b] ON [a].[AspNetUserId] = [b].[Id]
INNER JOIN [AspNetUserRoles] AS [c] ON [b].[Id] = [c].[UserId]
INNER JOIN [AspNetRoles] AS [d] ON [a].[RoleId] = [d].[Id]
内连接的代码有效但我想要左连接....:
var query = (
//INNER JOIN
from a in _dbCtx.AppUser
join b in _dbCtx.Users
on a.AspNetUserId equals b.Id
////LEFT JOIN
join c in _dbCtx.UserRoles
on b.Id equals c.UserId
// // //LEFT JOIN (if you wanted right join the easiest way is to flip the order of the tables.
join d in _dbCtx.Roles
on a.RoleId equals d.Id
select new
{
AppUserId = a.AppUserId,
//Email = b.Email,
FirstName = a.FirstName,
MiddleName = a.MiddleName,
LastName = a.LastName,
IsInternal = a.IsInternal,
AspNetUserId = a.AspNetUserId,
PictureLink = a.PictureLink,
SignatureLink = a.SignatureLink,
PhoneNumber = a.PhoneNumber,
Extension = a.Extension,
FaxNumber = a.FaxNumber,
MobileNumber = a.MobileNumber,
Skype = a.Skype,
//Role = d.Name != null ? string.Empty :d.Name ,
SupervisorId = a.SupervisorId,
BackUpId = a.BackUpId,
HasAutoAssignClaims = a.HasAutoAssignClaims,
IsActive = a.IsActive
}).ToList();
使用左连接的代码...我错过了一些概念不起作用
什么不起作用是在g2.RoleId等于d.Id进入group3线g2不可用.那么我将如何为我的下一次左连接提供c.RoleId？基本上在你分组之后你显然不能再使用它了.
var LeftJoin= (
//INNER JOIN
from a in _dbCtx.AppUser
join b in _dbCtx.Users
on a.AspNetUserId equals b.Id
////LEFT JOIN
join c in _dbCtx.UserRoles
on b.Id equals c.UserId into group2
from g2 in group2.DefaultIfEmpty() //makes it left join
join d in _dbCtx.Roles
on g2.RoleId equals d.Id into group3
from g3 in group3.DefaultIfEmpty()
select new
{
AppUserId = a.AppUserId,
Email = b.Email,
FirstName = a.FirstName,
MiddleName = a.MiddleName,
LastName = a.LastName,
IsInternal = a.IsInternal,
AspNetUserId = a.AspNetUserId,
PictureLink = a.PictureLink,
SignatureLink = a.SignatureLink,
PhoneNumber = a.PhoneNumber,
Extension = a.Extension,
FaxNumber = a.FaxNumber,
MobileNumber = a.MobileNumber,
Skype = a.Skype,
Role = g3.Name != null ? string.Empty :g3.Name ,
SupervisorId = a.SupervisorId,
BackUpId = a.BackUpId,
HasAutoAssignClaims = a.HasAutoAssignClaims,
IsActive = a.IsActive
}).ToList();
这是一种通过非常糟糕的查询生成数据的解决方法。它生成一系列对数据库的调用，这些调用确实会产生相同的结果集。然而，这绝对不是该工作的最佳查询。我还在等待 RC2，我会更新答案。
var query = (
//INNER JOIN
from a in _dbCtx.AppUser
join b in _dbCtx.Users
on a.AspNetUserId equals b.Id
from c in _dbCtx.UserRoles
.Where(x => b!=null && x.UserId == b.Id)
.DefaultIfEmpty()
from d in _dbCtx.Roles
.Where(x => a !=null && x.Id == a.RoleId)
.DefaultIfEmpty()
select new
{
AppUserId = a.AppUserId,
Email = b.Email,
FirstName = a.FirstName,
MiddleName = a.MiddleName,
LastName = a.LastName,
IsInternal = a.IsInternal,
AspNetUserId = a.AspNetUserId,
PictureLink = a.PictureLink,
SignatureLink = a.SignatureLink,
PhoneNumber = a.PhoneNumber,
Extension = a.Extension,
FaxNumber = a.FaxNumber,
MobileNumber = a.MobileNumber,
Skype = a.Skype,
Role = d.Name != null ? string.Empty :d.Name ,
SupervisorId = a.SupervisorId,
BackUpId = a.BackUpId,
HasAutoAssignClaims = a.HasAutoAssignClaims,
IsActive = a.IsActive
}).ToList();