Understanding datetime formats in SQL Server

I've dealt with MS SQL Server datetime types for a long time but never thought why the following is happening: 1. I query a table that contains a smalldatetime column. This smalldatetime is always returned in the format yyyy-MM-dd hh:mm:ss 2. Now I write a different query on which I want to apply a smalldatetime filter in the WHERE clause, something like WHERE TimeStamp >= 'yyyy-MM-dd hh:mm:ss' 3. SQL Server retrieves an error and tells me that was not possible to convert that nvarchar to a valid smalldatetime It appears that it only works if I change the specified format and I write it using the european format, like WHERE TimeStamp >= 'dd-MM-yyyy hh:mm:ss'. Why is SQL Server showing me the dates in a format that is not covertable or valid when applied back to itself? I don't have any problem in changing the date format when writing queries, but I want to play with these dates at an application level (Java-JDBC app) and I don't want to be applying date format changes all the time... Could anyone explain me why this is happening and if there is any way to solve it at a DB level? Thanks!! Edit: Please see the screenshot of the error in Management Studio below.