How to lamdbda expression causes repeat records in C#?

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ID:  

1

2

3

InsertTable:  

first insert:  1  12  Flower  A

two insert  :  1  12  Flower  A
               2  12  Flower  A

third insert:  1  12  Flower  A
               2  12  Flower  A
               3  12  Flower  A

Result:
               1  12  Flower  A

               1  12  Flower  A

               2  12  Flower  A

               1  12  Flower  A

               2  12  Flower  A

               3  12  Flower  A

I want to Result :  1   12  Flower  A

                    2   12  Flower  A

                    3   12  Flower  A

What I have tried:

var query=MyStudentEntities.Student.OrderBy(x=>x.ID).Where(x=>x.ClassID="12").GroupBy(x=>x.ID).Distinct();


foreach(var item in query)
{
    students.Add(new TABLEA()
{
  ID=item.ID,
  ClassID=12,
  ClassName="Flower",
  ClassBranch="A"
});

MyStudentEntities.TABLEA.AddRange(students);
MyStudentEntities.SaveChanges();
}

Posted 17-Dec-19 8:05am

Member 14169626

Updated 18-Dec-19 2:40am

v2

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Comments

ZurdoDev 17-Dec-19 14:08pm

This is going to get closed very quickly unless you ask a question.

Member 14169626 17-Dec-19 14:15pm

why I double-lost in the query I made him I want to add as 1 2 3

ZurdoDev 18-Dec-19 7:37am

What does that mean?

Maciej Los 17-Dec-19 14:56pm

Did you check what the below query returns?

var query=MyStudentEntities.Student.OrderBy(x=>x.ID).Where(x=>x.ClassID="12").GroupBy(x=>x.ID).Distinct();

Simon_Whale 17-Dec-19 15:38pm

From looking at this I have one question. are you inserting all these rows each time or are you just trying to add a "new row" each call?

Member 14169626 17-Dec-19 23:18pm

one by one.
every time I add it, it adds the same one I added

Maciej Los 18-Dec-19 2:15am

Please, use "Reply" widget (on the right side of nick/login) to inform user about your reply.

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Maciej Los · Answer 1 · 2019-12-18T02:41:00

Try to change your code as follow:

C#

var data=MyStudentEntities.Student
    .Where(x=>x.ClassID==12)
    .GroupBy(x=>x.ID)
    .Select(grp=>new TABLEA()
        {
          ID=grp.Key,
          ClassID=12,
          ClassName="Flower",
          ClassBranch="A"
        })
    .ToList();

MyStudentEntities.TABLEA.AddRange(data);
MyStudentEntities.SaveChanges();