MS SQL -Date and Time Style conversion problem

Question

I need to convert Date and Time Style from USA format to German and than cast that into int data type. So for variable in case below this works fine if I want to display it in Standard 112 (ISO)

DECLARE @LoopDate datetime
SET @LoopDate = '12/23/2015'
SELECT @LoopDate AS Original, 
CAST(CONVERT(VARCHAR(8), @LoopDate, 112) AS int) AS int;

But when I put 104 which suppose to gives me error:

Conversion failed when converting the varchar value '23.10.2015' to data type int.

It looks like conversion is actually working but casting into int is not.

Answer 1

The 104 format has . in it and thats why it is failing vs the 112 has not dots so you can cast that as int. See https://learn.microsoft.com/en-us/sql/t-sql/functions/cast-and-convert-transact-sql?view=sql-server-2017

DECLARE @LoopDate datetime
SET @LoopDate = '12/23/2015'
SELECT @LoopDate AS Original,
CONVERT(VARCHAR(8), @LoopDate, 104) as GermanDate_WithDot, -- see the dot  
 cast(replace(CONVERT(VARCHAR(8), @LoopDate, 104),'.','') as int)  as ProperlyCastedGermanDate_WithoutDot,
CAST(CONVERT(VARCHAR(8), @LoopDate, 112) AS int) AS ISOCasted_Date_asInt  ;

Note: Casting date to int for some later math is not a good idea.