add data in datagrid

Hi,
I have a problem, please help me to solve it.
I want to make a column in a datagrid and that column get data from two column beside. For example i want make a column that get data from amount two column beside. That data will display when I insert new row. I use a datatable in my datagrid.

When i add new row, there will be error.

It would be better for you to do all calculations in the SQL query itself before you attach the result to the datagrid.So if u want to do some calculations on one column and show it in another column,it will be easy for you if do it in the query itself.Hope this helps.

Add a DataColumn to the table. Set a name to it, and then set the Expression proeprty of it to be "columnA * columnB" where those are the names of the two columns. You can see an example in MSDN:

Code:

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private void CalcColumns(){
    DataColumn cPrice;
    DataColumn cTax;
    DataColumn cTotal;
    DataTable myTable = new DataTable ();
 
    // Create the first column.
    cPrice = new DataColumn();
    cPrice.DataType = System.Type.GetType("System.Decimal");
    cPrice.ColumnName = "price";
    cPrice.DefaultValue = 50;
       
    // Create the second, calculated, column.
    cTax = new DataColumn();
    cTax.DataType = System.Type.GetType("System.Decimal");
    cTax.ColumnName = "tax";
    cTax.Expression = "price * 0.0862";
       
    // Create third column.
    cTotal = new DataColumn();
    cTotal.DataType = System.Type.GetType("System.Decimal");
    cTotal.ColumnName = "total";
    cTotal.Expression = "price + tax";
   
    // Add columns to DataTable.
    myTable.Columns.Add(cPrice);
    myTable.Columns.Add(cTax);
    myTable.Columns.Add(cTotal);
    DataRow myRow;
    myRow = myTable.NewRow();
    myTable.Rows.Add(myRow);
    DataView myView = new DataView(myTable);
    dataGrid1.DataSource = myView;
 }

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remember to remove the column before you update to database.