In Windows Form

	Bt_Click
		{
			try
				{
					getFromBC();//Class Business Layer 
				}
			catch (Exception ex)
            			{
                			//Handle Error;
            			}
		}

In Class Business Layer 


	public string getFromBC()
		{
			try
				{
					string str1 = callFunction1();//Class Business Layer 
					string str1 = callFunction2();//Class Business Layer 
					string str1 = callFunction3();//Class Business Layer 

				}
			catch (Exception ex)
            			{
                			//Do nothing, move it to layer up;
            			}
		}

	private void callFunction1
		{
			try
				{
					callForProcedure1();//Class Data Layer
				}
			catch (Exception ex)
            			{
                			//Do nothing, move it to layer up;
            			}
		}

In Class Data Layer 

	private string callFunction1
		{
			try
				{
					callSP1();
				}
			catch (Exception ex)
            			{
                			Throw ex;
            			}
		}