Question

I’m have a web application, that creates an Access database.
When I’m creating this database, I first have to delete the file if it exists and then recreate it.

            if (File.Exists(DataSourcePath + fileName))
                File.Delete(DataSourcePath + fileName);

            string cnnStr = @"Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + DataSourcePath + fileName + "; Jet OLEDB:Engine Type=5";
            var catType = Type.GetTypeFromProgID("ADOX.Catalog");
            object o = Activator.CreateInstance(catType);
            catType.InvokeMember("Create", BindingFlags.InvokeMethod, null, o, new object[] { cnnStr });

            OleDbConnection cnn = new OleDbConnection(cnnStr);
            var cmd = cnn.CreateCommand();

            cnn.Open();
            cmd.CommandText = "CREATE TABLE TblInfoCompany (Name TEXT, Family TEXT)";
            cmd.ExecuteNonQuery();

            cmd.Dispose();
            cnn.Close();
            cnn.Dispose();

When I’m recreating this file, I can get an exception.
Exception says: “The file is used in another process.”
Please help me to close this process or to find any way to solve this problem.

Thanks.

Answer 1

The process mantaining the file in use is probably the web application itself. Since closing/opening that mdf file is not directly handled by you, but from the Jet Engine, it is not so easy. I would suggest to PInvoke the system function MoveFileEx specifying:

• null as a second parameter meaning you want to delete
• MOVEFILE_DELAY_UNTIL_REBOOT as dwFlags, meaning the operation would be done at next system restart

I know is not the best since server are not so frequently shut down, but is probably the simpler solution to delete a locked file you can’t close elseway.