I used to open sdf (sqlCE) files with visual-studio? or sql-server? I really don\'t remember. Now I can\'t open this sdf file. With what program do I need to open it?
You can use SQL Compact Query Analyzer
http://sqlcequery.codeplex.com/
SQL Compact Query Analyzer is really snappy. 3 MB download, requires an install but really snappy and works.