Cannot open SQLite database-Collection of common programming errors

11 years ago

admin

1 minute

Using this code:

public void InsertPlatypiRequestedRecord(string PlatypusId, string PlatypusName, DateTime invitationSentLocal)
{
    var db = new SQLiteConnection(SQLitePath);
    {
        db.CreateTable();
        db.RunInTransaction(() =>
                                {
                                    db.Insert(new PlatypiRequested
                                                  {
                                                      PlatypusId = PlatypusId,
                                                      PlatypusName = PlatypusName,
                                                      InvitationSentLocal = invitationSentLocal
                                                  });
                                    db.Dispose();
                                });
    }
}

…I get, “SQLite.SQLiteException was unhandled by user code HResult=-2146233088 Message=Cannot create commands from unopened database“

…but attempting to add a “db.Open()” doesn’t work, because there is apparently no such method.

You are disposing the database prematurely (inside of the transaction). It is better to wrap things up inside of a “using” statement, which will dispose of the db connection:

private void InsertPlatypiRequestedRecord(string platypusId, string platypusName, DateTime invitationSentLocal)
{
    using (var db = new SQLiteConnection(SQLitePath))
    {
        db.CreateTable();
        db.RunInTransaction(() =>
        {
            db.Insert(new PlatypiRequested
            {
                PlatypusId = platypusId,
                PlatypusName = platypusName,
                InvitationSentLocal = invitationSentLocal
            });
        });
    }
}

string connecString = @"Data Source=D:\SQLite.db;Pooling=true;FailIfMissing=false";       
/*D:\sqlite.db??sqlite????????,???????????*/
SQLiteConnection conn = new SQLiteConnection(connectString); //??????
conn.Open();  //????
SQLiteCommand cmd = conn.CreateCommand();

cmd.CommandText = "select * from orders";   //?????????orders?

cmd.CommandType = CommandType.Text;
using (SQLiteDataReader reader = cmd.ExecuteReader())
{
   while (reader.Read())
                Console.WriteLine( reader[0].ToString());
}

you can download System.Data.SQLite.dll here

here is a chinese article for csharp connect sqlite