我想在linq表达式中格式化嵌套的左联接。我已经下载了LINQPad4，但是它似乎没有能力将SQL转换为linq。
我不明白如何获得嵌套的左联接。我试图用'into'子句操纵表达式无济于事。
Linq表情
from cli in Clients
join er in EntityRelationships on cli.EGUID equals er.ParentID
join con in Contacts on er.ChildID equals con.EGUID
join erEmail in EntityRelationships on er.EGUID equals erEmail.ParentID into erIfAny
from r in erIfAny.DefaultIfEmpty()
join ea in EmailAddresses on r.ChildID equals ea.EGUID
join eaDefault in EntityDefaultValues on r.ID equals eaDefault.RelationshipID
where cli.ClientID == 6
select new
{
ContactID = con.ContactID,
ContactLastName = con.ContactLastName,
ContactFirstName = con.ContactFirstName,
ContactTitle = con.ContactTitle,
EmailAddress = ea
}).Distinct()
产生以下SQL语句
DECLARE @p0 Int = 6
SELECT DISTINCT con.*, ea.*
FROM Clients AS cli
INNER JOIN EntityRelationships AS er ON cli.eGUID = er.ParentID
INNER JOIN Contacts AS con ON er.ChildID = con.eGUID
LEFT OUTER JOIN EntityRelationships AS erEmail ON er.eGUID = erEmail.ParentID
INNER JOIN EmailAddresses AS ea ON erEmail.ChildID = ea.eGUID
INNER JOIN EntityDefaultValues AS eaDefault ON erEmail.ID = eaDefault.RelationshipID
WHERE cli.ClientID = @p0
但是，我需要将左后的两个内部连接像这样包裹在左内。
DECLARE @p0 Int = 6
SELECT DISTINCT con.*, ea.*
FROM Clients AS cli
INNER JOIN EntityRelationships AS er ON cli.eGUID = er.ParentID
INNER JOIN Contacts AS con ON er.ChildID = con.eGUID
LEFT OUTER JOIN EntityRelationships AS erEmail
INNER JOIN EmailAddresses AS ea ON erEmail.ChildID = ea.eGUID
INNER JOIN EntityDefaultValues AS eaDefault ON erEmail.ID = eaDefault.RelationshipID
ON er.eGUID = erEmail.ParentID
WHERE cli.ClientID = @p0
我的linq表情应该是什么样？
编辑：
不知道我能做到这一点，但最终我只是写了内联SQL。
var query = db.Database.SqlQuery<ContactViewModel>(
"select distinct con.*, ea.Value as EmailAddress " +
"from Clients AS cli " +
"join EntityRelationships AS er ON cli.eGUID = er.ParentID " +
"join Contacts AS con ON er.ChildID = con.eGUID " +
"left join EntityRelationships AS erEmail " +
"join EmailAddresses AS ea ON erEmail.ChildID = ea.eGUID " +
"join EntityDefaultValues AS eaDefault ON erEmail.ID = eaDefault.RelationshipID " +
"on er.eGUID = erEmail.ParentID " +
"where cli.ClientID=" + cID.ToString() + " " +
"order by con.ContactLastName, con.ContactFirstName");
参考方案
对于人们来说，尝试获取LINQ代码以匹配他们过去使用的SQL是一个非常常见的错误。由于SQL仅限于扁平化的结果集，而面向对象的代码可以表示更丰富的层次数据，因此，如果您不再对SQL方面的问题进行过多思考，则很可能可以在LINQ查询中更好地建模您真正想要的东西。
我不完全确定您要在这里做什么，但通常LINQ中的左外连接最终看起来像一个对象，而其属性之一具有其他对象：
from cli in Clients
where cli.ClientID == 6
join er in EntityRelationships on cli.EGUID equals er.ParentID
join con in Contacts on er.ChildID equals con.EGUID
select new
{
ContactID = con.ContactID,
ContactLastName = con.ContactLastName,
ContactFirstName = con.ContactFirstName,
ContactTitle = con.ContactTitle,
Emails =
from erEmail in EntityRelationships
where er.EGUID == erEmail.ParentID
join ea in EmailAddresses on r.ChildID equals ea.EGUID
where EntityDefaultValues.Any(eaDefault => r.ID == eaDefault.RelationshipID
select ea
}
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