Modifying a DataTable

Question

Situation:

Hello! I am trying to populate a WPF toolkit DataGrid with a MS Access database.

Here is what I have right now (it works):

//Load the datagrid with the database
    private void LoadDataGrid(string filename, string path)
    {
        string databaseConn = "Provider=Microsoft.ACE.OLEDB.12.0;" +
                              "Data Source=" + path + "\\" + filename,
               tableName ="";
        OleDbConnection conn = null;
        DataTable schemaTable,
                  table = new DataTable();

        try
        {
            conn = new OleDbConnection(databaseConn);
            try
            {
                conn.Open();
                schemaTable = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables,
                                                       new object[] { null, null, null, "TABLE" });
                tableName = "[" + schemaTable.Rows[0].ItemArray[2].ToString() + "];";
                string sqlQuery = "SELECT * FROM " + tableName;
                OleDbCommand command = new OleDbCommand(sqlQuery, conn);
                OleDbDataReader reader;
                reader = command.ExecuteReader();
                table.Load(reader);
                DataGrid_.ItemsSource = table.DefaultView;
            }
            catch (Exception ex)
            {
                System.Windows.MessageBox.Show(ex.Message); 
            }
            finally
            {
                conn.Close();
            }
        }
        catch (Exception ex)
        {
            System.Windows.MessageBox.Show(ex.Message); 
        }
    }

The code sample above loads a WPF toolkit DataGrid with the help of a MS Access database.

What I would like to do is be able to insert a column in the DataGrid at the very beginning. This column would be used to write the row number. What I think could work is to modify the table variable (which is a DataTable object).

---

Question:

So, how can I insert a column in the table variable, add the row number for each rows in that new column, and have all the data from the database in the DataGrid?

Answer 1

Your easiest solution would be to modify your code to include a "virtual" RowNumber field in your original SELECT query, like so:

SELECT ROWNUM AS ROWNUMBER, * FROM TABLE1

Unfortunately, Access doesn't have anything like a ROWNUM function, so I think the easiest solution is to add a RowNumber column in the SELECT query like this:

SELECT 0 AS ROWNUMBER, * FROM TABLE1

which will add a column containing all zeroes at the beginning, and then iterate through the resulting DataTable and set the row number, like this:

int rownumber = 1;
foreach (DataRow row in table.Rows)
{
    row["ROWNUMBER"] = rownumber;
    rownumber++;
}

and then dump the DataTable into the grid.

Answer 2

An alternative is to create a column on the DataTable before loading the IDataReader into it.

// the rest of your code
//
DataTable table = new DataTable();
DataColumn col = table.Columns.Add("RowNumber", typeof(int));
col.AutoIncrementSeed = 1;
col.AutoIncrement = true;

//
// the rest of your code
//

table.Load(reader)
//
// the rest of your code

The code snippet bellow demonstrates the technique out of the question's context

//Simulates data coming from a database or another data source
DataTable origin = new DataTable(); 
DataColumnCollection columns = origin.Columns; 
columns.Add("Id", typeof(int)); 
columns.Add("Name", typeof(string)); 
origin.Rows.Add(55, "Foo"); 
origin.Rows.Add(14, "Bar"); 
IDataReader reader = origin.CreateDataReader();

DataTable table = new DataTable(); 

//Sets up your target table to include a new column for displaying row numbers
//These are the three lines that make it all happen.
DataColumn col = table.Columns.Add("RowNumber", typeof(int)); 
col.AutoIncrementSeed = 1; 
col.AutoIncrement = true; 

//Simulates loading data from the database
table.Load(reader); 

// Examine table through the debugger. Is will have the contents of "origin" with the column "RowNumber" prepended