2 dimensional string array to SQLite database table

public int SQLiteArrayToTable(string[,] array, string tablename, SQLiteConnection sqlcon, string[] columnnames = null)
        {
            string[] colnames;
            SQLiteCommand cmd = new SQLiteCommand();

            /*if caller passed an array of column names, use it else create a default array*/
            if ((columnnames == null))
            {
                colnames = new string[array.GetUpperBound(1) + 1];
                for (int i = 0; i <= colnames.GetUpperBound(0); i++)
                {
                    colnames[i] = "Col_" + i.ToString();
                }
            }
            else
            {
                colnames = new string[columnnames.GetUpperBound(0) + 1];
                for (int i = 0; i <= columnnames.GetUpperBound(0); i++)
                {
                    colnames[i] = columnnames[i];
                }
            }

            /*build a string to create a database table*/
            string CreatTableString = "CREATE TABLE " + tablename + "(";
            for (int i = 0; i <= colnames.GetUpperBound(0); i++)
            {
                CreatTableString += colnames[i] + " char(128),";
            }

            /*trim last comma from end of string*/
            CreatTableString = TrimRight(CreatTableString, 1);
            CreatTableString += ")";

            /*create the table*/
            try
            {
                cmd = new SQLiteCommand(CreatTableString, sqlcon);
                cmd.ExecuteNonQuery();
            }
            catch (SQLiteException)
            {
                if (cmd.Connection != null)
                {
                    cmd.Dispose();
                   
                }
				/*fail*/
				return -1;
            }

            /*create and build a transaction query*/
            cmd = new SQLiteCommand();
            cmd.Connection = sqlcon;
            SQLiteTransaction sqltrans;
            sqltrans = sqlcon.BeginTransaction();
            cmd.Transaction = sqltrans;

            try
            {
                for (int y = 0; y <= colnames.GetUpperBound(0); y++)
                {
                    string tnames = "";
                    for (int x = 0; x <= array.GetUpperBound(1); x++)
                    {
                        tnames += colnames[x] + ",";
                    }

                    /*trim last comma from end of string*/
                    tnames = TrimRight(tnames, 1);

                    string tvalues = "";
                    for (int x = 0; x <= array.GetUpperBound(1); x++)
                    {
                        tvalues += '"' + array[y, x] + '"' + ",";
                    }

                    /*trim last comma from end of string*/
                    tvalues = TrimRight(tvalues, 1);
                    
                    
                    string sql = "INSERT INTO " + tablename + "(" + 
                        tnames + ") VALUES (" +
                        tvalues +  ")";

                    
                    
                    cmd.CommandText = sql;
                    cmd.ExecuteNonQuery();
                    
                }

                /*commit the transaction*/
                sqltrans.Commit();

            }
            catch (Exception)
            {
                sqltrans.Dispose();
                cmd.Dispose();
                sqltrans.Rollback();
                return -2;
            }

            /*success*/
            sqltrans.Dispose();
            cmd.Dispose();
            return 0;
        }


private string TrimRight(string s, int count)
        {
            int len = s.Length;

            if (count < 0)
            {
                return s;
            }

            if (count >= len)
            {
                return "";
            }
            return s.Substring(0, len - count);
        }