when learning the knowledge of mysql penetration, the attempt to read the file on disk D with sql statement failed as follows:

root@host

after testing, the value of secure-file-priv is not valid even if it is empty.

mysql,apache is running normally

I really can"t find the point of the problem

document mean that the file must be on the server? does it mean on your own computer?

I am a rookie, asking for advice