Database

<br />
private void frmEmployees_Load(object sender, System.EventArgs e)<br />
		{<br />
			try<br />
			{<br />
				cnn.Open();<br />
				//Fill the DataSet with the Employee details<br />
				OleDbCommand cmd = cnn.CreateCommand();<br />
				cmd.CommandType = CommandType.Text;<br />
				cmd.CommandText = "SELECT * FROM Employee";<br />
				da.SelectCommand = cmd;<br />
				//Gets all the details for the database, e.g. Primary keys<br />
				da.FillSchema(ds,SchemaType.Source,"Employee");<br />
				da.Fill(ds,"Employee");<br />
				<br />
				//Fill the DataSet wtih the Department details<br />
				cmd.CommandText = "SELECT * FROM Department";<br />
				da.SelectCommand = cmd;<br />
				da.FillSchema(ds,SchemaType.Source,"Department");<br />
				da.Fill(ds,"Department");<br />
				<br />
				//Assign the parent column of the Department table and child column of the<br />
				//employee table. Remember - DepartmentCode PK in Department table, and <br />
				//FK in the Employee Table.<br />
				DataColumn parentColumn = ds.Tables["Department"].Columns["DepartmentCode"];<br />
				DataColumn childColumn = ds.Tables["Employee"].Columns["DepartmentCode"];<br />
				<br />
				//Clear the relation of any data. Not really nessessary as we are creating from new.<br />
				//However, if we are to reuse then we must clear all contents.<br />
				ds.Relations.Clear();<br />
				drEmployees = new DataRelation("EmployeeDetails",parentColumn,childColumn);<br />
				ds.Relations.Add(drEmployees);<br />
				<br />
				//Display the details of the first employee in the database.<br />
				txtEmployeeID.Text = ds.Tables["Employee"].Rows[0]["EmployeeNumber"].ToString();<br />
				txtFirstName.Text = ds.Tables["Employee"].Rows[0]["FirstName"].ToString();<br />
				txtSurname.Text = ds.Tables["Employee"].Rows[0]["Surname"].ToString();<br />
				txtDateOfBirth.Text = ds.Tables["Employee"].Rows[0]["DateOfBirth"].ToString();<br />
				txtAddress1.Text = ds.Tables["Employee"].Rows[0]["Address1"].ToString();<br />
				txtAddress2.Text = ds.Tables["Employee"].Rows[0]["Address2"].ToString();<br />
				cboDepartment.Text = ds.Tables["Employee"].Rows[0]["DepartmentCode"].ToString();<br />
<br />
				string departmentCode = ds.Tables["Employee"].Rows[0]["DepartmentCode"].ToString();<br />
				DataRow[] departmentRow = ds.Tables["Department"].Select("DepartmentCode = '" + departmentCode + "' ");<br />
				string departmentName = departmentRow[0]["DepartmentName"].ToString();<br />
				<br />
				<br />
				this.UpdateDepartments();//Call to display combo box information<br />
			}	<br />
			catch ( OleDbException ex )<br />
			{<br />
				MessageBox.Show(ex.Message);<br />
			}<br />
			catch ( Exception ex )<br />
			{<br />
				MessageBox.Show(ex.Message);<br />
			}<br />
		}<br />

<br />
ds.Tables["Employee"].Rows[0]["FirstName"] = txtFirstName.Text;<br />
ds.Tables["Employee"].Rows[0]["Surname"] = txtSurname.Text;<br />
ds.Tables["Employee"].Rows[0]["DepartmentCode"] = departmentCode;<br />
<br />
da.Update(ds,"Employee"); //Error ocurrs here<br />