To be notice MS SQL supports only UCS-2 encoding so do not have encoding with UTF-8 as we expected as MySQL or some other database server as well. This means that you can't use UTF-8 character encoding with Microsoft SQL Server:
Here after I type Khmer Unicode and execute the query, I got question marks instead of characters:

So if you need to store national characters in Microsoft SQL Server - please consider using a national character encoding (
U+1780 to U+17FF in Unicode/ISO10646 for Khmer Unicode characters, for example). Change data types:
- varchar to nvarchar
- text to ntext
- char to nchar
Here is the example since I created a table and insert data:
1. Create database (mtr_db) as normally (default setting)

2. Create table (tblunicode) with two fields (id/name) but
name - data type
nvarchar(MAX)

3. Insert Khmer Unicode and execute we got it as we typed!

Good luck!