# # show the global and session values; # select @@global.old; --error ER_INCORRECT_GLOBAL_LOCAL_VAR select @@session.old; show global variables like 'old'; show session variables like 'old'; select * from information_schema.global_variables where variable_name='old'; select * from information_schema.session_variables where variable_name='old'; # # show that it's read-only # --error ER_INCORRECT_GLOBAL_LOCAL_VAR set global old=1; --error ER_INCORRECT_GLOBAL_LOCAL_VAR set session old=1;