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How can I set the primary key value to other col in table when I insert a new row in SQL Server

I am using LINQ-to-SQL class. I am inserting a new row using LINQ method object.InsertOnSubmit().
I need to set same value which is generate by SQL Server (using Identity) for table primary key column.
Now I need the same value at the time of inserting new row into table. And set the same value for other column in the same table at the time of insert only.
As I cannot update as after inserting because table has UPDATE TRIGGER.
I tried the following
_db.EmpNews.InsertOnSubmit(_EmpNews);
...
_db.DisplaySeq = _EmpNews.ID;
...
_db.SubmitChanges();
Where ID is the auto-generated (Identity) column.

The first question really is: why would you need to store the same value in two separate columns in the same table? What do you need this for? Doesn't seem to make a lot of sense to me....
Since the value of the IDENTITY column is only available once the row has actually been inserted, there is no way to get that value and set it to another column before the row has indeed been saved to the database table.
That basically leaves three options to get that value and store it somewhere else:
you can write an AFTER INSERT trigger that just set the other column to the value that's just been inserted in the IDENTITY column
you could wrap the whole saving process into a stored procedure which you call from your C# code (instead of just saving the object) and you would do the INSERT of the row, then get the newly created IDENTITY value and update the row again with that new value. But that would cause an UPDATE to happen - which you seem to say is impossible for you because of an UPDATE trigger (not quite clear on why this should be a problem....)
you can write two lines of C# code to get the IDENTITY value after it's been inserted (and available in the ID property of your object) and then store the object a second time. But that, too, would cause an UPDATE to happen - which you seem to say is impossible for you because of an UPDATE trigger (not quite clear on why this should be a problem....)
So I guess your best option would be an INSERT trigger to do this.
Try something like this:
CREATE TRIGGER trInsertEmpNews
ON dbo.EmpNews AFTER INSERT
AS BEGIN
UPDATE dbo.EmpNews
SET DisplaySeq = i.ID
FROM INSERTED i
WHERE dbo.EmpNews.ID = i.ID
END

Dataset autoincrement issue

I have a SQL Server Database with several tables. One of them has "ID" (primary key), "Name" and other columns that i won't mention here for sake of simplicity. "ID" column is auto increment, unique and when i add some row using "SQL Server management studio", "ID" column increments properly. Database is old and current auto increment is at 1244 or so.
Now, i have created a C# project that uses TYPED Dataset to work with data from database. My database starts empty, dataset is filled using table adapters, new rows are added using my program but there's a problem i have never stumbled upon so far: when my program adds new row to Dataset, then updates database (using table adapter), "ID" column in my database gets correct auto-incremented number (1245,1246 etc), BUT my "ID" column in dataset gets "-1", "-2" instead! What's the problem? How can i tell my dataset to use auto-increment seed specified by database instead generating it's own NEGATIVE (???) primary key numbers?
EDIT:
I get and compare rows using this:
dsNames.tbNamesRow[] TMP = basedataset.tbNames.Select() as dsNames.tbNamesRow[];
foreach (dsNames.tbNamesRow row in TMP)
{
string Name = row.Name;
bool Found = Name == Search;
if (CompareDelegate != null)
Found = CompareDelegate(Name, Search);
if (Found)
{
int ID = row.ID;
break;
}
}

My original comment was kind of incorrect, I assumed you were retrieving the value from the database and THAT dataset had incorrect values in it.
The way ADO.NET deals with preventing collisions with it's disconnected dataset, it assigns negative IDENTITY column values, because it wouldn't know a possible positive number that IS NOT a collision as it's disconnected. These (negative) values are unique in terms of that transaction.
When you try and commit your changes, the ADO.NET engine determines the proper SQL to produce the correct result.

Adding a new item to a DataSet, writing it to Access DB

I'm having an issue with writing back to my Access Database (.accdb) through using a DataAdapter.
Currently, I have a Fill method which fills a DataSet Table up with data. This piece of code is currently sitting within my Form_Load().
// TODO: This line of code loads data into the 'hCAliasDataSet.Topics' table. You can move, or remove it, as needed.
this.topicsTableAdapter.Fill(this.hCAliasDataSet.Topics);
Then I have an cmdAdd_Click() event, this is obviously to add a new row into the Topcis table that sits within the hCAliasDataSet.
// Create a new row, append it to Topics table.
DataRow DR;
DR = this.hCAliasDataSet.Tables["Topics"].NewRow();
this.hCAliasDataSet.Tables["Topics"].Rows.Add(DR);
Next, I've created some code to caputre the input of one of the column values.
// Capture user input
sTopicName = Interaction.InputBox("Please Enter Topic Name", "Topic Name", null, 100, 100);
// Set the Topic value for the new Row
DR["Topic"] = sTopicName;
My problem, I'm assuming is here, where I call the dataAdapter to update the Topics table. I manually check the database, and there aren't any new rows created?
// Commit the changes back to the hCAlias DataBase (hcalias.accdb).
this.topicsTableAdapter.Update(this.hCAliasDataSet.Topics);
Edit: I believe I'm needing to create an INSERT query, for my TableAdapter, would this be correct?

The adapter should generate the insert statement automatically for you behind the scenes.
Your code looks right, but it's possible that you have a constraint on one of your columns that makes it unable to save. (like a non-nullable column that you didn't specify any data for). But, you'd usually get an exception if there was a constraint that cancelled the insert.
You can try one of these alternatives, but they're basically the same thing:
this.topicsTableAdapter.Update(this.hCAliasDataSet);
this.topicsTableAdapter.Update(DR);
this.topicsTableAdapter.Insert(sTopicName); // add any other columns in here

You should call AcceptChanges in your dataset:
hCAliasDataSet.AcceptChanges();
And then commit to the database with your TableAdapter.

The Update() method just updates existing records, you'll need to use the TableAdapter Insert() method to add a new row. VC# will have created a default Insert() method for you, (which may be overloaded)... but there will be a method that will let you explicitly insert values....
For example...
this.topicsTableAdapter.Insert(int Column1, string Column2 etc etc)
This will create a new row in your database and populate it with the values you specify.

Writing to the database from LINQ in C#

I am trying to write some content to my database via LINQ. Currently, I'm getting the following error:
Cannot insert explicit value for identity column in table 'MyTable' when IDENTITY_INSERT is set to OFF.
I understand this is a primary key related issue. My table has the identity specification set to "Yes" with Identity Increment set to "1". But I have successfully updated other tables using code that looks like the following:
using (DataModelDataContext context = new DataModelDataContext())
{
List<MyTable> newRecords = new List<MyTable>();
MyTable record1 = new MyTable();
record1.CreatedBy = GetUserName();
record1.Information = GetInformation();
newRecords.Add(record1);
MyTable record2 = new MyTable();
record2.CreatedBy = GetUserName();
record2.Information = GetInformation();
newRecords.Add(record2);
context.MyTables.InsertAllOnSubmit(newRecords);
context.SubmitChanges();
}
What would cause this error? If I want to write new records, is there a way to set the primary key before it gets sent to the db? Something like "GetNextKey()" or something? Basically, I just need to insert these records. What am I doing wrong?
Thanks!

The code you have posted would work, assuming neither of those fields have the identity value. You basically need to assure you do not try to set the identity value before you add the item to the Table collection. (actually, you should never set the identity value from your code in most circumstances when it is to be generated in the DB).
So somewhere, the code that is having an error is trying to set the identity field's value.

If the ID is important (say you're importing data, and records you'll be inserting later will reference these records), then turn off the identity temporarily while you perform the insert. If having a particular ID on each record doesn't matter, and you can let the identity column pick one (which is 99.9 percent of the time), make sure you're not specifying a value for the ID before trying to save the record. Also make sure that your mapping between the object and the DB specifies that the ID is an identity, so EF knows not to try to insert the ID column.

Check to make sure your primary key/identity column has the following set within the DBML:
Auto Generated Value: True
Auto-Sync: OnInsert
This will make sure that LINQ-To-SQL will not try and insert the key value into that column and that it will update the value after an insert takes place. These should be on when you added the table to the DBML.

Strange Problem with updating Database from Dataset

Operations:
Delete in DataGridView selected row from Dataset:
FuDataSet.FuRow row = (FuDataSet.FuRow) ((DataRowView)FuBindingSource.Current).Row;
row.Delete();
To add a new Row I'm doing:
FuDataSet.FuRow row = FuDataSet.Fus.NewFuRow();
row.Someting = "Some initial Content";
row.SomethingElse = "More Initial Content";
...
FuDataSet.Fus.AddFuRow(row);
Saving user changes in current row in Dataset:
FuDataSet.FuRow row = (FuDataSet.FuRow) (((DataRowView) FuBindingSource.Current).Row);
row.Someting = someTextBox.text;
...
Save in Database:
Validate();
FuBindingSource.EndEdit();
FuTableAdapter.Update(FuDataSet.Fus); <-- Exception here
I'm using the standard DatagridView, Dataset, TableAdapter, BindingSource Scheme VS puts automaticly up after defining the database structure. There is only a single table involved and SQL Server compact 3.5 is used.
Now my problem is that I get a Concurrency Exception (DeletedRowInaccessibleException) each time I'm doing this (starting with an empty database):
Creating a new row, delete this row, save in Database, new row, save in database, delete this row, save in database <- Exception
I think that there is some synchroniszing problem between the database and the dataset.
If I'm reloading the databse after each save via FuTableAdapter.Fill(FuDataSet.Fus) the problem is gone. However, this cannot be the intention I think.
I hope someone can help me out and spot a failure in the design or explain me what may go wrong.
Thank you!

Does your table have an auto increment identity column as the primary key? If so it might not be updating the dataset table with the new value after the insert, so when you come to delete it, it cannot find the row in the database. That could explain why it works once you called the Fill() method.
You will need to somehow return the primary key on the insert so that the dataset table stays in sync with database. If you are using a store procedure to do the inserts, then primary key can be returned using an out parameter. Not sure what the best way is if you are using an SQL insert statement in the command, but you will then have to get the primary key back from the database table and assign it to the database table row.
Not sure if you are doing this after the saveing, but calling FuDataSet.AcceptChanges() will help the dataset track new changes after the database has been updated.

What you have listed there is correct. When a new row is created in the dataset table, it creates it's own ID. When you save to the database, the database table creates it's own ID as well, which in most cases will be different to the one in the dataset.
When you created the table adapter for that table, you had to supply a sql state to create the dataset table. On the advanced Options button, there is a checkbox called "Refresh the data table". Check that to have a sql statement added after the insert and update to retrieve the identity column.
If the checkbox is disabled then I am not sure what else you could, other than reload the data after each save, which will not be optimal.
Sorry I cannot be of more assistance. Best of luck