SQL Server - Multi language data support

Problem:

I used CKEditor to edit my pages. Then, I stored the content of the pages to SQL Server 2008 database. The page contents should support in different languages such as English, German and Vietnamese. I met a problem when I worked on Vietnamese pages.
The text was successfully saved but it was displayed wrong when reading again from database, likes the following:
Input: "Ðây là Tiếng Việt"
Display: "Ðây là Ti?ng Vi?t".

Solution:

We need to use nvarchar (nchar | ntext) data type for strings  and we also need to precede all unicode strings with 'N'

Here is my code:

 
--create table 
CREATE TABLE [dbo].[xedu_page_content](
  [id] [numeric](11, 0) IDENTITY(1,1) NOT NULL,
  [category] [varchar](100) NOT NULL PRIMARY KEY,
  [content] [Ntext] NULL
 )

 --save
 BEGIN TRAN
 IF not exists (SELECT category FROM xedu_page_content
       WHERE category='"+in.categoryKey+"')
  INSERT INTO xedu_page_content(category,content)
   VALUES ('"+in.categoryKey+"',N'"+in.content+"');
 ELSE
  UPDATE xedu_page_content
   SET content = N'"+in.content+"'
   WHERE category='"+in.categoryKey+"'
 COMMIT

Reference:
[1]. http://stackoverflow.com/questions/2017198/sql-server-multi-language-data-support
[2]. http://msdn.microsoft.com/en-us/library/ms186939.aspx