public class DbConnectionFactory
    {
        public static DbConnection CreateConnection(ConnectionData connectionData)
        {
            var connectionString = BuildConnectionString(connectionData);
            if (connectionData.DbSystem == DbSystem.Postgres)
            {
                return new NpgsqlConnection(connectionString);
            }
            return new FbConnection(connectionString);
        }
        private static string BuildConnectionString(ConnectionData cs)
        {
            if (cs.DbSystem == DbSystem.Postgres)
            {
              return $"User ID={cs.UserId};Password={cs.Password};Host={cs.Server};Port={cs.Port};Database={cs.Database}";           //<=====  Postgre
            }
            return $"User={cs.UserId};Password={cs.Password};Database={cs.Database};DataSource={cs.Server};Port={cs.Port}";          //<=====  Firebird
        }
    }