vid pk db    name somedata
1    1  1   john1     5
2    2  1   mary1     3
3    3  1   john1     4
4    1  2   john2     1
5    2  2   mary2     2
6    3  2   john2     7

SQLiteConnection connector;
        SQLiteConnection cWeb;
        SQLiteConnection cUser;
string webdb = "webdb.db";
        string virtualdb = "virtual.db";
       string userdb = "user.db";

connector = new SQLiteConnection(string.Format("Data Source={0}", virtualdb));
cWeb = new SQLiteConnection(string.Format("Data Source={0}", webdb));
cUser = new SQLiteConnection(string.Format("Data Source={0}", userdb));
SQLiteCommand cmd = null;
            string createTableQuery = @"CREATE TABLE IF NOT EXISTS [cAuthors] (
                          [memid] INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
                          [id] INTEGER NULL,
                          [name] TEXT NULL,
                          [db] TEXT NULL
                          )";

cmd = new SQLiteCommand(createTableQuery, connector);
cmd.ExecuteNonQuery();
cmd = new SQLiteCommand("ATTACH '" + userdb + "' AS userdb", connector);
cmd.ExecuteNonQuery();

cmd = new SQLiteCommand("INSERT INTO main.cAuthors (id, name, db) VALUES (SELECT id FROM userdb.Authors, SELECT name FROM userdb.Authors, '2')", connector);
cmd.ExecuteNonQuery();