select @@global.report_host;
@@global.report_host
NULL
select @@session.report_host;
ERROR HY000: Variable 'report_host' is a GLOBAL variable
show global variables like 'report_host';
Variable_name	Value
report_host	
show session variables like 'report_host';
Variable_name	Value
report_host	
select * from performance_schema.global_variables where variable_name='report_host';
VARIABLE_NAME	VARIABLE_VALUE
report_host	
select * from performance_schema.session_variables where variable_name='report_host';
VARIABLE_NAME	VARIABLE_VALUE
report_host	
set global report_host=1;
ERROR HY000: Variable 'report_host' is a read only variable
set session report_host=1;
ERROR HY000: Variable 'report_host' is a read only variable