/**
     * Method for checking if a sheep with ID already exists in the database.
     * @param sheep_id ID to be checked in the database.
     * @return Return a boolean value of the result.
     */
    public boolean sheepExists(int sheep_id){
        openConnectionToDatabase();
        int id = -1;
        try{
            stmt.executeQuery("SELECT sau_id FROM SauInfo WHERE sau_id="+sheep_id+";");
            rs = stmt.getResultSet();

            if(rs.next()){
                id = rs.getInt(1);
                if(id == sheep_id){
                    return true;
                }
            }

        }catch(SQLException ex){
            System.out.println("(sheepExists)SQLException: " + ex.getMessage());
            System.out.println("(sheepExists)SQLState: " + ex.getSQLState());
            System.out.println("(sheepExists)VendorError: " + ex.getErrorCode());
        }finally{
            closeConnectionToDatabase();
        }
        return false;
    }