LEFT OUTER JOIN in LINQ To SQL

re: LEFT OUTER JOIN in LINQ To SQL

James Price — Tue, 18 Mar 2008 21:55:21 GMT

Good explanation. Thanks.

re: LEFT OUTER JOIN in LINQ To SQL

James Hancock — Mon, 26 May 2008 19:03:02 GMT

Wow, that has to be the dumbest, most complex syntax I have ever seen for something that should be trivial.

how about leftjoin and rightjoin anyone? MS I can't believe you punish us this much for using LINQ!

re: LEFT OUTER JOIN in LINQ To SQL

John — Mon, 02 Jun 2008 17:58:31 GMT

Thanks for your help! This link also helped bring me up to speed on this topic: http://blogs.msdn.com/vbteam/archive/2008/01/31/converting-sql-to-linq-part-8-left-right-outer-join-bill-horst.aspx

re: LEFT OUTER JOIN in LINQ To SQL

wizalex — Tue, 10 Jun 2008 10:07:03 GMT

It seems to me that code:

ar query= from c in db.Customers

where c.CustomerID.StartsWith("B")

join o in db.Orders on c.CustomerID equals o.CustomerID into sr

from x in sr.DefaultIfEmpty()

select new {CustomerID= c.CustomerID, ContactName=c.ContactName, OrderID = x.OrderID == null ? -1 : x.OrderID};

will not work properly - Exception of type 'System.NullReferenceException : Object reference not set to an instance of an object' might fire.

May be the best way is replace the part of code <b>'OrderID = x.OrderID == null ? -1 : x.OrderID' </b> to next: <b>'OrderID = x == null ? -1 : x.OrderID'<b>

re: LEFT OUTER JOIN in LINQ To SQL

Tuantt — Wed, 05 Nov 2008 23:03:46 GMT

I find mistake from "OrderID = x.OrderID == null ? -1 : x.OrderID". Could you check it again?

Thank alot!

re: LEFT OUTER JOIN in LINQ To SQL

Denny — Mon, 10 Nov 2008 18:56:41 GMT

wizalex is correct, you want:

OrderID = (x == null) ? -1 : x.OrderID

because in a left join if the value does not exist it will return null, which is what this line does:

from x in sr.DefaultIfEmpty()

in this case x can be (default) null and therefore you would not be able to reference x.OrderId

re: LEFT OUTER JOIN in LINQ To SQL

Upender — Mon, 01 Dec 2008 04:15:38 GMT

Hi Frnds

I am using the same code with MySql like you.I am getting a error 'Lambda Parameter not in scope'

Please help me

re: LEFT OUTER JOIN in LINQ To SQL

Nick — Wed, 28 Jan 2009 13:51:15 GMT

Love the variable naming ...."x" classic

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Left outer join in Entity Framework | Ideas and Coffee at 3.47 AM — Thu, 25 Mar 2010 23:44:58 GMT

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C#: Left outer joins with LINQ « Mehroz’s Experiments

C#: Left outer joins with LINQ « Mehroz’s Experiments — Wed, 14 Apr 2010 13:00:03 GMT

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