LINQ GroupBy

Hi Experts,

I need your help to add grouping by T.tid   in this code. Thank you in advance.


                    var mydata = db.data
                   
                    .Where(T => T.some.Any(F => F.my_id == another_id))
                   
                    .ToArray()
                 
                    .Select(T => new MyInfo
                    {
                        TId = T.tid,
                        PData = T.data
                       
                     
                    }).ToArray();
LVL 1
fpoyavoAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Fernando SotoRetiredCommented:
Hi fpoyavo;

What is the data type of T.tid? Because if you create a grouping it will return a hierarchical data object. What is also the data type of MyInfo.Tid? Because it will need to store that object.

Can you show in a diagram what you want that grouping to look like or what you need it to look like.
0
fpoyavoAuthor Commented:
T.tid is int. MyInfo.Tid is int. MyInfo.PData is string.
0
Fernando SotoRetiredCommented:
So what are you trying to accomplish by grouping in the query?
0
Rowby Goren Makes an Impact on Screen and Online

Learn about longtime user Rowby Goren and his great contributions to the site. We explore his method for posing questions that are likely to yield a solution, and take a look at how his career transformed from a Hollywood writer to a website entrepreneur.

fpoyavoAuthor Commented:
To eliminate duplicated data
0
Fernando SotoRetiredCommented:
Grouping will not get rid of duplicates. When you say duplicates does that mean that all columns having the same values or certain columns only.
0
fpoyavoAuthor Commented:
Some of them. Not all.
0
Fernando SotoRetiredCommented:
Hi fpoyavo;

The IEqualityComparer below is used to see if two rows in the database table can be considered duplicates. The IEqualityComparer is only considering two columns to test whether they are considered duplicates or not. If more columns are needed to determine  if they are duplicate then you must add those columns as well.

// See comment below
var ec = new OrderEqualityComparer();

// In the query you need to add the Distinct method after the first ToArray.
var mydata = db.data
               .Where(T => T.some.Any(F => F.my_id == another_id))
               .ToArray()
               .Distinct(ec)
               .Select(T => new MyInfo
               {
                   TId = T.tid,
                   PData = T.data              
               }).ToArray();

// This class is used to match two data object from the database table
// data to see if they are considered duplicates.               
class OrderEqualityComparer : IEqualityComparer<data>
{

    public bool Equals(data d1, data d2)
    {
        if (d1.TID == d2.TID & d1.OtherCoulmn == d2.OtherCoulmn)
        {
            return true;
        }
        else
        {
            return false;
        }
    }


    public int GetHashCode(data d)
    {
        int hCode = d.TID.GetHashCode() ^ d.OtherCoulmn.GetHashCode();
        return hCode.GetHashCode();
    }

}

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
.NET Programming

From novice to tech pro — start learning today.