I'm trying to import a CSV file (UTF-8 encoding) in Ruby (2.0.0) in to my database (MSSQL 2008R2, COLLATION French_CI_AS), but the special characters (French accents on vowels) are not stored properly : éèçôü becomes éèçôü (or other similar jibberish).
I use this piece of code to read the file :
CSV.foreach(file, col_sep: ';', encoding: "utf-8") do |row|
   # ...
end
I tried various encoding in the CSV options (utf-8, iso-8859-1, windows-1252), but none would store the special characters correctly. 
Before you ask, my database collation supports those characters, since we have successfully imported data containing those using PHP importers. If I dump the data using puts or a file logger, everything is correct.
Is something wrong with my code, or do I need to specify something else (like the ruby class file encoding for example) ?
Thanks
EDIT : The data saving is done by a PHP REST API that works fine with accented characters. It stores data as it is received.
In Ruby, I parse my data, store it in an object and then send the JSON-encoded object in the body of my PUT request. But if I use an SQL query directly from Ruby, the problem remains :
query = <<-SQL
    UPDATE MyTable SET MyTable_title = '#{row_data['title']}' WHERE MyTable_id = '#{row_data['id']}'
SQL
res = db.execute query