public static class DataReaderExtensions
{
    public static IEnumerable<T> Stream<T>(this IDbCommand command, Func<IDataRecord, T> converter)
    {
        using (var reader = command.ExecuteReader(CommandBehavior.SingleResult))
        {
            while (reader.Read())
                yield return converter(reader);
        }
    }

    public static Nullable<T> ValueOrNull<T>(this IDataRecord record, string field) where T : struct
    {
        var value = record[field];
        if (value == DBNull.Value)
            return new Nullable<T>();

        return (T)value;
    }

    public static T ValueOrDefault<T>(this IDataRecord record, string field)
    {
        var value = record[field];
        if (value == DBNull.Value)
            return default(T);

        return (T)value;
    }

    public static long? Long(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (long)value;
    }

    public static string String(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (string)value;
    }

    public static Guid? Guid(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (Guid)value;
    }

    public static DateTime? Date(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (DateTime)value;
    }

    public static int? Int(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (int)value;
    }

    public static bool? Boolean(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        if (value is bool)
            return (bool)value;

        if (value is int)
            return ((int)value) == 1;

        return Convert.ToBoolean(value);
    }

    public static long? RowVersion(this IDataRecord record, string column)
    {
        object value = record[column];
        if (value == DBNull.Value)
            return null;

        // can't use BitConverter as value coming out is big-endian
        byte[] bytes = (byte[])value;
        long ret = 0;
        for (int i = 0; i < 8; i++)
        {
            ret = unchecked((ret << 8) | bytes[i]);
        }

        return ret;
    }

    public static decimal? Decimal(this IDataRecord record, string column)
    {
        var value = record[column];
        if (value == DBNull.Value)
            return null;

        return (decimal)value;
    }

    public static byte[] Binary(this IDataRecord record, string column)
    {
        int idx = record.GetOrdinal(column);
        if (record.IsDBNull(idx))
            return null;

        // copy data into memory
        using (var memory = new MemoryStream())
        {
            int bufferSize = 4096;
            byte[] buffer = new byte[bufferSize];
            int offset = 0;

            while (true)
            {
                // read in the data and increment our offset
                long length = record.GetBytes(idx, offset, buffer, 0, bufferSize);
                offset += bufferSize;

                // write the resulting bytes to the memory stream
                memory.Write(buffer, 0, (int)length);
                    
                // if we didn't read full buffer, then we are likely done
                if (length < bufferSize)
                    break;
            }

            return memory.ToArray();
        }
    }
}