DECLARE @nstring nchar(8)
SET @nstring = N'你好'
SELECT UNICODE(SUBSTRING(@nstring, 2, 1)), 
NCHAR(UNICODE(SUBSTRING(@nstring, 2, 1)))

/*
Result is:
	----------- ---- 
	22909       好

	(1 row(s) affected)

Where 22909 = 0x597D, which is in fact the code of the string's 2nd character: "好" (hao3).
*/