SELECTING empty months

Hi,

In my application users have to enter in data once a month. I need to
try and create a query where I can see what months are filled in but
then I need to return the missed months.

I've got up to where I have the dates that are missed, but how do I
return them as a result set? The variable @EMPTY_MONTHS contains the
missed months but I just need to know how to put them in a result set
and return them?

DECLARE @INSTALLATION_DATE DateTime
DECLARE @NO_MONTHS int
DECLARE @EMPTY_MONTHS varchar(50)
DECLARE @COUNTER int
DECLARE @TABLE_NAME varchar(50)

SET @TABLE_NAME         = '__After_Hours_Monthly'
SET @INSTALLATION_DATE  = (Select Installation_Date From
__Installation_Date)
SET @NO_MONTHS          = DATEDIFF(m,@INSTALLATION_DATE,GETDATE())

WHILE @NO_MONTHS > 0
        BEGIN
                SET @INSTALLATION_DATE  =
DATEADD(mm,1,@INSTALLATION_DATE)
                SET @NO_MONTHS          = @NO_MONTHS - 1
                SELECT * FROM __After_Hours_Monthly WHERE
DATEPART(m,EntryDate) = @INSTALLATION_DATE
                IF @@ROWCOUNT = 0
                        BEGIN
                                SET @EMPTY_MONTHS = @EMPTY_MONTHS + ','
+ CONVERT(VARCHAR,@INSTALLATION_DATE)
                        END     
        END