DataColumn sigma = table1.Columns.Add("Sigma", typeof(double));
DataColumn cpKL = table1.Columns.Add("CpKL", typeof(double));
DataColumn cpKR = table1.Columns.Add("CpKR", typeof(double));
DataColumn cpK = table1.Columns.Add("CpK", typeof(double));
sigma.Expression="(Convert(point90,'System.Double')-Convert(point10,'System.Double'))/2.56";
cpKL.Expression="(Convert(point50,'System.Double')-Convert(LSL,'System.Double'))/(3.0*sigma)";
cpKR.Expression="(Convert(USL,'System.Double')-Convert(point50,'System.Double'))/(3.0*sigma)";
cpK.Expression = "IIF(cpKL < cpKR, cpKL, cpKR)";