Save change from grid view to SQL

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C#

Hi i have problem
I use sql data i use table adappter to save change from grud view to sql tables
This for fill

////--TO FILL FORM AGAIN FROM SQL AFTER UPDATE
//this.wELDING_SUMMARYTableAdapter.Fill(this.qA_QCSYSTEMDataSet3.WELDING_SUMMARY);

And thus for save and refill again

gridView1.CloseEditor();
            gridView1.UpdateCurrentRow();
            wELDINGSUMMARYBindingSource.MoveNext();
            this.wELDING_SUMMARYTableAdapter.Adapter.ContinueUpdateOnError = true;
            this.wELDING_SUMMARYTableAdapter.Update(this.qA_QCSYSTEMDataSet)
            this.wELDING_SUMMARYTableAdapter.Fill(this.qA_QCSYSTEMDataSet.WELDING_SUMMARY);

I have problem if 2 users update the file if user 1 update row1 and user 2 update row 2 and user1 save change then user2 save his changes he will save his change also read changes from user 1


But problem if user1 and user2 work in same row if first user save first then user 2 save the change from user 2 not saved only he will read change from user1
I don't know why
Can any one help me.

What I have tried:

I try to save by this code

gridView1.CloseEditor();
            gridView1.UpdateCurrentRow();
            wELDINGSUMMARYBindingSource.MoveNext();
            this.wELDING_SUMMARYTableAdapter.Adapter.ContinueUpdateOnError = true;
            this.wELDING_SUMMARYTableAdapter.Update(this.qA_QCSYSTEMDataSet);


            //TO BEST FIT ALL COLUMNS
            //gridView1.BestFitColumns();
            ///------- TO FILL DATA GRIDE VEIEW BY ALL TABLE OR AS PER TEXT BOX VALUE FOR SKETCH NO OR LINE ID OR LINE NO OR TEST PACKAGE SEIRAL OR NAME-----////
            this.wELDING_SUMMARYTableAdapter.Fill(this.qA_QCSYSTEMDataSet.WELDING_SUMMARY);