How to create an HDMI CEC - USB adapter with your own hands?

Question

HDMI

There is a solution in the form of a finished piece of iron: https://www.pulse-eight.com/p/104/usb-hdmi-cec-adapter
But it seems that you can do it yourself? All that is needed is the hdmi input port, we intercept the signal from the desired leg, we send everything else to another hdmi port for the computer. We listen to CEC signals and either transmit them via usb, or decode them and send them via usb in the form of commands understandable for the PC.
Or is it much more complicated? Question to the connoisseurs, is it worth trying, or is it better not to waste time on this? Plus, I would also like to implement power on / off, i.e. here one USB will not be enough, it will also be necessary to connect to the power button (laptop).

Answer 1

Use a subquery.
SELECT * FROM ( <your_query> ) ORDER BY <field_name> DESC

Answer 2

Does adding ORDER BY i.id DESC or ORDER BY p.id DESC at the end not help?
Or with grouping the cant is obtained?

Answer 3

The field alias is substituted in order by , which actually means that sorting is done after grouping. For example
order by product_id desc
Moreover, instead of an alias, you can use the serial number of the column in the output:
order by 2 desc

Answer 4

With grouping, the cant is obtained. ;-(