C#

private void btnAddColumn_Click(object sender, EventArgs e)
{
    conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source = T:\Nasmeea\PSSZ.mdb";
    conn.Open();
    DataAdapter = new OleDbDataAdapter("Select * From [DivInfo]", conn);
    DataColumn dValue = new DataColumn();
    DataTable dataTable = new DataTable("[DivInfo]");
    dValue.ColumnName = txtboxColumns.Text.ToString();
    dValue.DataType = Type.GetType("System.String");
    dataTable.Columns.Add(dValue);
    dataTable.AcceptChanges();
    conn.Close();
    MessageBox.Show("Column Added");
}

conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source = T:\Nasmeea\PSSZ.mdb";
conn.Open(); // This is Optional because DataAdapter will automatically open the given connection.
DataAdapter da = new DataAdapter("Select field1, field2 From [DivInfo]", conn);
DataTable dataTable = new DataTable("System_Setting"); // Creating Untype Datatable. Expected count of fields are 2.
da.Fill(dataTable); // Fill the datatable

//Adding two fields.
DataColumn dValue = new DataColumn();
DataColumn dMember = new DataColumn();
dValue.ColumnName = "dValue";
dValue.DataType = Type.GetType("System.String");
dMember.ColumnName = "dMember";
dMember.DataType = Type.GetType("System.String");
dataTable.Columns.Add(dValue);
dataTable.Columns.Add(dMember);
conn.Close(); // This is Optional because DataAdapter will automatically close the given connection.

MessageBox.Show("Column Count:" + dataTable.Columns.Count.ToString());
MessageBox.Show("Row Count:" + dataTable.Rows.Count.ToString());

System.Data.OracleClient.OracleConnection conn = new OracleConnection();
conn.ConnectionString = "Data Source=testDB;User ID=Claims;Password=claim2be;";
OracleDataAdapter da = new OracleDataAdapter("Select Key,Value From System_Setting", conn);
DataTable dataTable = new DataTable("System_Setting");
da.Fill(dataTable);
DataColumn dValue = new DataColumn();
DataColumn dMember = new DataColumn();
dValue.ColumnName = "dValue";
dValue.DataType = Type.GetType("System.String");
dMember.ColumnName = "dMember";
dMember.DataType = Type.GetType("System.String");
dataTable.Columns.Add(dValue);
dataTable.Columns.Add(dMember);

private void btnAddColumn_Click(object sender, EventArgs e)
{
    conn.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source = T:\Nasmeea\PSSZ.mdb";
    conn.Open();
    OleDbDataAdapter da = new OleDbDataAdapter("Select * From [DivInfo]", conn);
    DataTable dataTable = new DataTable("DivInfo");
    da.Fill(dataTable);
    DataColumn dValue = new DataColumn();
    dValue.ColumnName = txtboxColumns.Text.ToString();
    dValue.DataType = Type.GetType("System.String");
    dataTable.Columns.Add(dValue);
    dataTable.AcceptChanges();
    conn.Close();
    MessageBox.Show("Column Count:" + dataTable.Columns.Count.ToString());
    MessageBox.Show("Row Count: " + dataTable.Rows.Count.ToString());
}

MessageBox.Show("Column Count:" + dataTable.Columns.Count.ToString());            
MessageBox.Show("Row Count: " + dataTable.Rows.Count.ToString());