cast to NVARCHAR(MAX) causes "chinese"/UTF encoded characters

Question

I am using code like this in my SELECT statement:

CAST(HASHBYTES(N'SHA1', Bla) AS NVARCHAR(MAX)) AS hashed_bla

and end-up with "chinese"/UTF encoded characters in the ssms grid but also in upstream apps. Is there a way to change this? Does this have to do with the collation? Thanks!

Answer 1

What you have is working as expected. Take the following example:

SELECT HASHBYTES('SHA1','B8187F0D-5DBA-4D43-95FC-CD5A009DB98C');

This returns the varbinary value 0xA04B9CB18A2DC4BC08B83FCCE48A0AF1A1390756 . You are then converting that value to an nvarchar , so get a result like N'䮠놜ⶊ별레찿諤㦡嘇' (on my collation). For an varbinary each 4 characters represents a single character. So, for the above A04B is the first character (which is N'䮠' ).

It appears what you are after is an varchar representing a varbinary value (you don't need an nvarchar here, as there will be no unicode characters). To do so, you need to use CONVERT and a style code. For the example I gave above that would be:

SELECT CONVERT(varchar(100),HASHBYTES('SHA1','B8187F0D-5DBA-4D43-95FC-CD5A009DB98C'),1);

Which returns the varchar value '0xA04B9CB18A2DC4BC08B83FCCE48A0AF1A1390756' . If you don't want the '0x' at the start, use style code 2 , rather than 1 .