VB.NET LINQ to XML Left Join with ambiguous column name - vb.net

Question

I need to write a LINQ TO XML query, which queries two XML files exported from Access database tables. The original Access DB query looks like this:
SELECT
(
[TableB].[Code] Is Null,[TableA].[Code],
LCase(Left([TableA].[Code],1)) & ":" & [TableB].[code]
) AS Code,
Trim
(
[TableB].[Description] & " " & [TableA].[Description]
) AS Description
FROM TableA LEFT JOIN TableB
ON TableA.Code = TableB.SubProduct;
When I convert it to LINQ to XML, I have the problem of the right part of the left join is not available. My LINQ look like this:
Dim results = _
From a In TableA.Descendants("Product")
Group Join b In TableB.Descendants("Product")
On a.Element("Code").Value Equals b.Element("SubProduct").Value Into leftJoinGroup Group
From p In leftJoinGroup.DefaultIfEmpty
Select New With
{
I DON KNOW HOW TO WRITE IT
}
Both tables have the column named "Code". However, the variable TableB seems to be unavailable inside my Selectclause. I only have a and p available so I can't get the Code from TableB (b). How should I do that?

Answer 1

I just started using linq myself and ran into this issue last week. This was very helpful for me http://msdn.microsoft.com/en-us/vstudio/bb688088.aspx but here is an example of how to perform a left outer join in vb.net http://msdn.microsoft.com/en-us/vstudio/bb737909#lojoin.
In your example tableB is being stored into leftJoinGroup which your selecting from using p. To get values from tableB you will need to select from p and since your trying to concatenate the columns from both tableA and tableB, I would check if tableB record is null.
Dim results = From a In TableA.Descendants("Product") Group Join b In TableB.Descendants("Product") _
On a.Element("Code").Value Equals b.Element("SubProduct").Value Into leftJoinGroup = Group _
From p In leftJoinGroup.DefaultIfEmpty() _
Select New With { _
.Code = If(p Is Nothing, a.Element("Code").Value, String.Format("{0}:{1}", Left(a.Element("Code").Value.ToLower(), 1), p.Element("Code").Value)), _
.Description = If(p Is Nothing, a.Element("Description").Value, String.Format("{0} {1}", p.Element("Description").Value, a.Element("Description").Value))}
Here is an example of your code above, I didn't tested it. I've used this code when joining datatables not xdocuments. Sorry if this isn't clear this my first post here.