Transacting MS Access query (using IIF() and DATESERIAL()) into T-SQL - tsql

Question

I'm trying to convert some MS Access queries to T-SQL to use in SSIS (basically converting Access db to SQL server 2008) and I'm having trouble converting an IIF() statement. I tried several approaches and it always resulted in an error.
The query creates a column with dates that are "original Date + 2 years if the condition is met and original Date + 1 if the condition is not met". The first part of the IIF() eliminates the case of the original year being a leap year and so the possibility of generating a non-existing date.
The original IIF() statement is:
IIf((Day(Date)=29 And Month(Date)=2),
IIf(Desc Like "*" & "123" & "*",
DateSerial(Year(Date)+2,Month(Date),Day(Date)-1),
DateSerial(Year(Date)+1,Month(Date),Day(Date)-1)),
IIf(Desc Like "*" & "123" & "*",
DateSerial(Year(Date)+2,Month(Date),Day(Date)),
DateSerial(Year(Date)+1,Month(Date),Day(Date)))) AS Term
So the problem is not only an IIF() statement but also DATESERIAL function. I found the solution for the DATESERIAL() function using CAST() (SQL server 2008 does not have the DATEFROMPARTS() function...).
I tried using CASE() like this:
CASE
WHEN DAY(Date)=29 AND Month(Date)=2 THEN
CASE
WHEN Desc LIKE "%123%" THEN
CAST(CAST(YEAR(Date)+2 AS VARCHAR(4)) + RIGHT('0' + CAST(MONTH(Date) AS VARCHAR(2)), 2) + RIGHT('0' + CAST(DAY(Date)-1 AS VARCHAR(2)), 2) AS DATETIME )
ELSE CAST(CAST(YEAR(Date)+1 AS VARCHAR(4)) + RIGHT('0' + CAST(MONTH(Date) AS VARCHAR(2)), 2) + RIGHT('0' + CAST(DAY(Date)-1 AS VARCHAR(2)), 2) AS DATETIME ) END
ELSE CASE
WHEN Desc LIKE "%123%" THEN
THEN CAST(CAST(YEAR(Date)+2 AS VARCHAR(4)) + RIGHT('0' + CAST(MONTH(Date) AS VARCHAR(2)), 2) + RIGHT('0' + CAST(DAY(Date) AS VARCHAR(2)), 2) AS DATETIME )
ELSE CAST(CAST(YEAR(Date)+1 AS VARCHAR(4)) + RIGHT('0' + CAST(MONTH(Date) AS VARCHAR(2)), 2) + RIGHT('0' + CAST(DAY(Date) AS VARCHAR(2)), 2) AS DATETIME )END END AS Term
I also tried using COAELSCE() but with no better outcome.
I really don't know if I have made some kind of syntax error or where the problem could be.
Thank you in advance for any help.
edit: I'll add error message I'm getting: Incorrect syntax near '...'. The '...' changes as I try different approaches, sometimes its ELSE, THEN etc.

Answer 1

SQL Server's DATEADD may help to simplify things here...
CASE WHEN (<your condition>)
THEN DATEADD(YEAR, 1, [OriginalDate])
ELSE DATEADD(YEAR, 2, [OriginalDate])
END
Should also cope with leap years too.

Answer 2

DateSerial is such a useful function to have around, just create your own.
I got my version from here:
CREATE FUNCTION dbo.DateSerial
(
#year int,
#month int,
#day int
)
RETURNS datetime
AS
BEGIN
DECLARE #date datetime
-- convert date by adding together like yyyymmdd
SET #date = cast(#year * 10000 + 101 AS char(8));
-- Add to date the proper months subtracting 1, since we used 1 as start instead of zero.
SET #date = dateadd(mm , #month - 1 , #date)
-- Add to date the proper days subtracting 1, since we used 1 as start instead of zero.
SET #date = dateadd(dd , #day - 1 , #date);
RETURN #date ;
END;
GO
Here is another way: Date serial in SQL?
Then use the function just as you did in Access.
Edit: just noticed that your outer IIF is to handle leap years. This is not needed when using dateadd().