问题:

when i try to update one table(GLOBAL_VARIABLES) from information_schema db,

i get an error :

Access denied for user 'root'@'localhost' to database 'information_schema'

Although I am root user with all privileges ,

how can i fix permission. ?

or how can i update this table ?

thanks.

回答1:

You can change the global variables using SET, and read them using SHOW.

See http://dev.mysql.com/doc/refman/5.0/en/using-system-variables.html for more info

回答2:

The INFORMATION_SCHEMA database is a "pseudo database" containing server-generated views and as far as I know, contains only read-only data. If you need to alter a variable, you need to go the standard way, see Per's answer. From the mySQL manual:

INFORMATION_SCHEMA is the information database, the place that stores information about all the other databases that the MySQL server maintains. Inside INFORMATION_SCHEMA there are several read-only tables. They are actually views, not base tables, so there are no files associated with them.

More detailed info on GLOBAL_VARIABLES here.