Need help with designing a query in ELinq

Question

This is my query:

Dim vendorId = 1, categoryId = 1
Dim styles = From style In My.Context.Styles.Include("Vendor") _
             Where style.Vendor.VendorId = vendorId _
             AndAlso (From si In style.StyleItems _
                      Where si.Item.Group.Category.CategoryId = _
                          categoryId).Count > 0 _
             Distinct

I have the feeling that I can improve the performance, cuz the above query is (correct me if I am wrong) performs 2 round-trips to the server; 1 time by the Count and then when it's executed.

I want to send this Count thing to the DB so it should be only one round trip to the server.

Even it's not the exact thing, this is actually what I need:

SELECT DISTINCT Style.* 
FROM Style INNER JOIN
    Vendor ON Style.VendorId = Vendor.VendorId INNER JOIN
    StyleItem ON Style.StyleId = StyleItem.StyleId INNER JOIN
    Item ON StyleItem.ItemId = Item.ItemId INNER JOIN
    [Group] ON Item.GroupId = [Group].GroupId INNER JOIN
    Category ON [Group].CategoryId = Category.CategoryId
WHERE (Style.VendorId = @vendorid) AND (Category.CategoryId = @CategoryId)

I wish I could use this SPROC (i.e. function import etc.), but I need to Include("Vendor"), which constraints me to do it with Linq.

Any kind of suggestion will be really welcommed!

Answer 1

It is probably not doing two trips to the database. It will get optimized before it is executed, and nothing gets executed until you try the read the data.

Normally I check the SQL that is created using SQL Profiler. I have also found LinqPad to be very usefull.