Question

I have two tables:

tbl_ClassFac:
ClassFacNo (Primary Key)
,FacultyID
,ClassID

tbl_EmpClassFac:
EmpID, (Primary Key)
DateImplement, (Primary Key)
ClassFacNo

I want to know all the Employees who are on a specific ClassFacNo. ie. All EmpID with a specific ClassFacNo… What I do is that I first search tbl_EmpClassFac with the EmpID supplied by the user. I store these datarows. Then use the ClassFacNo from these datarows to search through tbl_ClassFac.
The following is my code.

        empRowsCF = ClassFacDS.Tables["EmpClassFac"].Select("EmpID='" + txt_SearchValueCF.Text + "'");
        int maxempRowsCF = empRowsCF.Length;
        if (maxempRowsCF > 0)
        {
            foundempDT = ClassFacDS.Tables["ClassFac"].Clone();
            foreach (DataRow dRow in empRowsCF)
            {
                returnedRowsCF = ClassFacDS.Tables["ClassFac"].Select("ClassFacNo='" + dRow[2].ToString() + "'");
                foundempDT.ImportRow(returnedRowsCF[0]);
            }
        }
        dataGrid_CF.DataSource = null;
        dataGrid_CF.DataSource = foundempDT.DefaultView;

        ***returnedRowsCF = foundempDT.Rows;*** // so NavigateRecordsCF can be used

        NavigateRecordsCF("F");  // function to display data in textboxes (no importance here)

I know the code is not very good but that is all I can think of. If anyone has any suggestions please please tell me. If not tell me how do I copy all the Rows in a datatable to a datarow array ???

Answer 1

“How to copy all the rows in a datatable to a datarow array?”

If that helps, use the overload of Select without a parameter

DataRow[] rows = table.Select();

DataTable.Select()

Gets an array of all DataRow objects.

According to the rest of your question: it’s actually not clear what’s the question.

But i assume you want to filter the first table by a value of a field in the second(related) table. You can use this concise Linq-To-DataSet query:

var rows = from cfrow in tbl_ClassFac.AsEnumerable()
           join ecfRow in tbl_EmpClassFac.AsEnumerable()
           on cfrow.Field<int>("ClassFacNo") equals ecfRow.Field<int>("ClassFacNo")
           where ecfRow.Field<int>("EmpId") == EmpId
           select cfrow;
// if you want a new DataTable from the filtered tbl_ClassFac-DataRows:
var tblResult = rows.CopyToDataTable();

---

Note that you can get an exception at CopyToDataTable if the sequence of datarows is empty, so the filter didn’t return any rows. You can avoid it in this way:

var tblResult = rows.Any() ? rows.CopyToDataTable() : tbl_ClassFac.Clone(); // empty table with same columns as source table