Getting 'unable to open database file' with sqlite running under mono

Question

my first time posting.

I made a console application that run in the background, it was written in C# and I'm using sqlite3 to store its information. It's running under mono but I'm getting unable to open database file after running fine for a few days. Restart the application solve the issue but it will give me the same error after few days.

I suspect it was the connection not getting dispose after close so I added dispose after the connection.close() but still getting the same error. I also did some search and find out this thread have similar problem, I did what he said but still getting same error.

Any help will be appreciated.

Sorry for bad english

UPDATE : My Code

private static void ExecuteNonQuery(string query)
    {
        if (isrunningundermono == true)
        {
            SqliteConnection sqlcon = new SqliteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SqliteCommand sqlcmd;

            sqlcon.Open();
            sqlcmd = sqlcon.CreateCommand();
            sqlcmd.CommandText = query;
            sqlcmd.ExecuteNonQuery();
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();
        }
        else
        {
            SQLiteConnection sqlcon = new SQLiteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SQLiteCommand sqlcmd;

            sqlcon.Open();
            sqlcmd = sqlcon.CreateCommand();
            sqlcmd.CommandText = query;
            sqlcmd.ExecuteNonQuery();
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();
        }
    }

    private static int ExecuteScalar(string query)
    {
        if (isrunningundermono == true)
        {
            SqliteConnection sqlcon = new SqliteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SqliteCommand sqlcmd;

            sqlcon.Open();
            sqlcmd = sqlcon.CreateCommand();
            sqlcmd.CommandText = query;
            int total = Convert.ToInt32(sqlcmd.ExecuteScalar());
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();

            return total;
        }
        else
        {
            SQLiteConnection sqlcon = new SQLiteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SQLiteCommand sqlcmd;

            sqlcon.Open();
            sqlcmd = sqlcon.CreateCommand();
            sqlcmd.CommandText = query;
            int total = Convert.ToInt32(sqlcmd.ExecuteScalar());
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();

            return total;
        }
    }

    private static DataTable ExecuteDataSet(string query)
    {
        if (isrunningundermono == true)
        {
            DataTable dt = new DataTable();
            SqliteConnection sqlcon = new SqliteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SqliteCommand sqlcmd = new SqliteCommand(sqlcon);
            sqlcon.Open();
            sqlcmd.CommandText = query;
            SqliteDataReader reader = sqlcmd.ExecuteReader();
            dt.Load(reader);
            reader.Close();
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();

            return dt;
        }
        else
        {
            DataTable dt = new DataTable();
            SQLiteConnection sqlcon = new SQLiteConnection(ConfigurationManager.AppSettings["connectionString"]);
            SQLiteCommand sqlcmd = new SQLiteCommand(sqlcon);
            sqlcon.Open();
            sqlcmd.CommandText = query;
            SQLiteDataReader reader = sqlcmd.ExecuteReader();
            dt.Load(reader);
            reader.Close();
            sqlcon.Close();
            sqlcmd.Dispose();
            sqlcon.Dispose();

            return dt;
        }
    }

    public static bool IsRunningOnMono()
    {
        return Type.GetType("Mono.Runtime") != null;
    }

Please show the code you use.

mbarthelemy
– mbarthelemy

2014-01-23 14:29:44 +00:00
Commented Jan 23, 2014 at 14:29 — mbarthelemy
– mbarthelemy, Commented Jan 23, 2014 at 14:29
hi, i just update my post and added the code.

tickwave
– tickwave

2014-01-24 03:46:35 +00:00
Commented Jan 24, 2014 at 3:46 — tickwave
– tickwave, Commented Jan 24, 2014 at 3:46

lesscode · Accepted Answer · 2014-01-24 04:17:35Z

1

SQLiteConnection.Dispose internally just calls SQLiteConnection.Close, so you're still effectively closing the connection before the command, which I guess is the problem on Mono. I think if you just remove the explicit calls to sqlcon.Close you'd see a better result.

By the way, it's customary to employ the using statement when dealing with IDisposable instances, eg:

using (var conn = new SQLiteConnection(...))
{
  conn.Open();
  using (var cmd = new SQLiteCommand(conn))
  {
  }
}

I think it's natural to dispose of the command before the connection, since the command uses the connection (and the using statement helps to keep this straight), but I see no reason why the reverse would work on Windows but not on Mono...

answered Jan 24, 2014 at 4:17

lesscode

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1 Comment

tickwave Over a year ago

thanks for the answer, will give results in a few days.

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