Linq order by clause

///----Order By Descending & then OrderBy Ascending (with 2 columns)
DataTable dtOrderTemp = DTAllPODetails.AsEnumerable().Where(i => i.Field<String>("Order Code").Contains(
  dtOrderCollection.Rows[ordercount][0].ToString().Trim())).OrderByDescending(i => i.Field<String>("GroupCode")).ThenBy(i => i.Field<int>("SerialNo")).CopyToDataTable();
                        

LinQ Distinct property

 var distinctPOValues = excelDataTable.AsEnumerable().Select(row => new
                    {
                        DistinctPO = row.Field<string>("PO Code"),
                        DistinctOrderNo = row.Field<string>("Order NO")
                    }).Distinct().ToList();
  
  // Distinct with where condition
 for (int i = 0; i < distinctPOValues.Count; i++)
 {
  var DistinctOrder = excelDataTable.AsEnumerable().Where(r => r.Field<string>("Buyer PO") == distinctPOValues[i].DistinctPO.ToString()
        ).Select(row => new
        {
            DistinctOrderCode = row.Field<string>("Order Code"),
            DistinctOrderNo = row.Field<string>("Order NO")
        }).Distinct().ToList();
 }

Linq Get value using first

/// Get cell value from dataTable with where condition.

decimal cst08 = dtOthers.AsEnumerable().First(x => x.Field<string>("Cost For") == "00008").Field<decimal>("Total Cost");
decimal cst49 = dtOthers.AsEnumerable().First(x => iManipulator.GetCode(x.Field<string>("Cost For")) == "00049").Field<decimal>("Total Cost");
                            
string headName = dtCstHead.AsEnumerable().First(x => x.Field<string>("code") == "00049").Field<string>("name") + "(00049)";                               
MessageBox.Show("Provided cost seem not valid. Please provide valid cost for " + headName + " on Others Tab");
                                
// get value from dataTable
var price = orderInfoDataTable.AsEnumerable().Where(p => p.Field<string>("Product Code") == cmbBin.Text.Trim()).Select(p => p.Field<decimal>("Price")).FirstOrDefault();

Linq sum with where

decimal cstSum = dtOthers.AsEnumerable().Where(c => iManipulator.GetCode(c.Field<string>("Cost For")) == "00021" 
|| iManipulator.GetCode(c.Field<string>("Cost For")) == "00038"
 iManipulator.GetCode(c.Field<string>("Cost For")) == "00046" 
 || iManipulator.GetCode(c.Field<string>("Cost For")) == "00053").Sum(c => c.Field<decimal>("Total Cost"));
                           

Linq Where clause

 /*
 1. You can't query against the DataTable's Rows collection, since DataRowCollection doesn't implement IEnumerable<T>. You need to use the AsEnumerable() extension for DataTable
 
 2. AsEnumerable() returns IEnumerable<DataRow>. If you need to convert IEnumerable<DataRow> to a DataTable, use the CopyToDataTable() extension. 
 */
 
 EnumerableRowCollection<DataRow> lcCombDataSource;
 EnumerableRowCollection<DataRow> scCombDataSource;

DataTable dtLcScTempList = new DataTable();
    if (!ChkAllLcSc.Checked)
         dtLcScTempList = dtLcScList.AsEnumerable().Where(c => c.Field<string>("Companycode") == iManipulator.GetCode(cmbCompany.Text.Trim()) 
                                        && c.Field<string>("Buyer_code") == iManipulator.GetCode(cmbByerName.Text)).CopyToDataTable();
    else
        dtLcScTempList = dtLcScList;

    if (lcScId == 0)
    {
        lcCombDataSource = dtLcScList.AsEnumerable().Where(c => c.Field<int>("Type") == (int)LcScType.Lc);

        scCombDataSource = dtLcScList.AsEnumerable().Where(c => c.Field<int>("Type") == (int)LcScType.Sc);
    }