USE Northwind
GO

SET NOCOUNT ON
CREATE TABLE numbers(n int)
CREATE TABLE Years(y int)
CREATE TABLE Customer(c char(1))
GO

INSERT INTO numbers(n) 
SELECT 1  UNION ALL
SELECT 2  UNION ALL
SELECT 3  UNION ALL
SELECT 4  UNION ALL
SELECT 5  UNION ALL
SELECT 6  UNION ALL
SELECT 7  UNION ALL
SELECT 8  UNION ALL
SELECT 9  UNION ALL
SELECT 10 UNION ALL
SELECT 11 UNION ALL
SELECT 12

INSERT INTO years(y) 
SELECT 2003  UNION ALL
SELECT 2004

INSERT INTO Customer(c)
SELECT 'X'
GO

CREATE TABLE myTable99(CustomerID char(1), [Month] int, [Year] int)
GO

INSERT INTO myTable99(CustomerID, [Month], [Year])
SELECT 'X', 5,  2003 UNION ALL
SELECT 'X', 6,  2003 UNION ALL
SELECT 'X', 7,  2003 UNION ALL
SELECT 'X', 8,  2003 UNION ALL
SELECT 'X', 9,  2003 UNION ALL
SELECT 'X', 11, 2003 UNION ALL
SELECT 'X', 12, 2003 UNION ALL
SELECT 'X', 1,  2004 UNION ALL
SELECT 'X', 2,  2004 UNION ALL
SELECT 'X', 3,  2004
GO

     SELECT XXX.c, XXX.n, XXX.y
       FROM (SELECT * FROM customer CROSS JOIN numbers CROSS JOIN years) AS XXX
  LEFT JOIN myTable99 t
	 ON t.[Month] = XXX.n
	AND t.[Year]  = XXX.y
      WHERE t.[Month] IS NULL 
	AND t.[Year]  IS NULL
GO

SET NOCOUNT ON
DROP TABLE Customer
DROP TABLE numbers
DROP TABLE years
DROP TABLE myTable99
GO