LINQ

There also other ways to speed up your queries, maybe this will help Entity Framework Performance[^] I know the language. I've read a book. - _Madmatt

It is an Anonymous Type containing properties of Number, Type, Table, Price and Date as requested in the final "select new { }" Linq expression. The var keyword was added specifically for this scenario.

Very nice! Indeed it works with the yield keyword to have the function return objects as long as there are 'descendants'.

I was in a hurry and forgt a small detaile in the GetLatestDate method. this is the good GetLatestDate: private DateTime GetLatestDate(List<Prices> prices, Item itm) { DateTime latest = new DateTime(1900, 1, 1); foreach (var price in prices) { if ((price.Date.CompareTo(latest)>0) && (price.ItemID.Equals(itm))) { latest = price.Date; } } return latest; }

" I have a fairly big XML database here and was wondering if I might get better performance by loading it into MySql." If I unterstood well, you want to "load" the xml file into MySQL witch means reading it and then loading it into the DB. If this is the case then it makes no sense. Just load it and LINQ it. If you want to give up the XML and use the DB taht's a totally different thing and it will be faster(a lot faster) especially for large amounts of data.

I am new to vb.net and LINQ. I do not understand what you understand when you said: "If I have 2 Lists of ints say ds1 and ds2 and in ds1 I put {1,1,2} and in ds2 I put {2} and then I use var except = ds1.Except(ds2) , except will contain only {1}. This I understand." I expected except to contain {1,1}. Please explain. What I am trying to do is this. Read a text file, exclude a group of words from the file and then use regex and linq to choose the words (maybe all words longer than 6 letters) count number of uses of a word and to group and order the output. Everything is working fine except the exclusion of words. I thought Except was the answer, but was very surprised to see that it removed duplicates from the target string. Any suggestions will be appreciated. Bill:confused:

I run into the same issue today, I solved it by calling dataset.AcceptChanges(); :)

I blogged about a DataSet/DataTable extension for Linq here[^]. "WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes. My blog | My articles | MoXAML PowerToys | Onyx

I can't understand how it works. Can you tell me where to find an example? Thanks, Silvia

That simple?? You for president!! Thanks! .: I love it when a plan comes together :. http://www.zonderpunt.nl

Oracle is Not supported!

Try the Sharepoint forum.

Use the ToList(); extension method. "WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes. My blog | My articles | MoXAML PowerToys | Onyx

The way I used to do it w/ LINQ2SQL is to generate an interface on the table, for each table class in the datacontext. I would then manually go through each interface and convert it to a class. I'm not sure if someone has figured out how to automate this. After a year of so, I bought a commercial ORM from Mindscape called Lightspeed, it supports linq and generates the DTOs for me =)

IMO this[^] is a must visit for anyone starting with LINQ. 50-50-90 rule: Anytime I have a 50-50 chance of getting something right, there's a 90% probability I'll get it wrong...!!

You only should get the foreign key of tableb! according to your example... unless you've selected some data of tableb like result.tableb.fieldOfTableB <--- this automatically makes a join in your query! ;)