Syntax:
LOAD_FILE(file_name)

Reads the file and returns the file contents as a string. To use this
function, the file must be located on the server host, you must specify
the full pathname to the file, and you must have the FILE privilege.
The file must be readable by all and its size less than
max_allowed_packet bytes.

If the file does not exist or cannot be read because one of the
preceding conditions is not satisfied, the function returns NULL.
