--source include/have_debug.inc
#
# exists both as global and session
#
set session debug_dbug="L";

select @@global.debug_dbug="1"; # just to show that global.debug exists
select @@session.debug;    # here we know the value and can display it
--replace_column 2 #
show global variables like 'debug';
show session variables like 'debug';
--replace_column 2 #
select * from information_schema.global_variables where variable_name="debug";
select * from information_schema.session_variables where variable_name="debug";

--error ER_WRONG_TYPE_FOR_VAR
set @@global.debug_dbug=1;
--error ER_WRONG_TYPE_FOR_VAR
set @@global.debug_dbug=1.1;
--error ER_WRONG_TYPE_FOR_VAR
set @@global.debug_dbug=1e1;