Question

I have an expression as “((ID + DepartmentID)*ID) as ExpressionColumn” where ID,department are the columns of a datatable. How to execute the expression for each datarow and add new column to the datatable as “ExpressionColumn”. Since the expression can vary based on User’s selection, Kindly help me with a generic code to calculate the expression for each row/column and add new column to the datatable.

Answer 1

Have a look at this example

DataTable dt = new DataTable();
dt.Columns.AddRange(new[] { new DataColumn("ID", typeof(decimal)), new DataColumn("DepartmentID", typeof(decimal)) });

for (int iRow = 0; iRow < 10 ; iRow++)
{
    DataRow dr = dt.NewRow();
    dr["ID"] = iRow;
    dr["DepartmentID"] = iRow;
    dt.Rows.Add(dr);
}
dt.Columns.Add(new DataColumn("Test", typeof (decimal), "((ID + DepartmentID)*ID)"));

Use the data visualizer before and after you add the last column (the calculated column).

You will notice by adding the calculated column, the calculations are done for you.