
Command Class
=============

Used to define a specific command (e.g a SQL query) intended to run
against a data source. The command syntax and semantics is defined 
by the data source only.
This is the root class of all operations done on the data sources.

Constructor
===========


Attributes
==========

   Bind      - Parameters of the command. Parameters refere 
               to place holders in the command string which
               are numbered by a positive number.

   Set       - Set a parameter to a fixed value
                   
   State     - Indicating the internal state of the command:
 
                    Idle      - No command associated with the command
                    Prepared  - The statement has been preparedby the 
				underlying source.
                    Executing -  data source still executing
                    Success   -  Succes

   Connection- the connection instance where this command is 
               created/prepared.

Methods
=======

   None 

Interfaces
==========

   The following abstract procedures are expected to be 
   implemented in the underlying command implementations:

   Open      - abstract interface to be implemented   
   Close     -
   Drop      -
     
Example
======= 

  con      : Connection....Object;
  cmd      : Command.Handle;

  X        : Integer;
begin

  Open( con, "......");
  
  cmd := Create_Query( 
       con, 
       "SELECT * FROM EMPLOYEES WEHRE empno > ? AND PROMOTION=?");
  Bind( cmd, 1, X );
  Set( cmd,  2, 1 );

  Result := Execute( cmd );

  Close( cmd );

end ;


