flush status;
show status like 'Table_lock%';
Variable_name	Value
Table_locks_immediate	0
Table_locks_waited	0
SET SQL_LOG_BIN=0;
drop table if exists t1;
create table t1(n int) engine=myisam;
insert into t1 values(1);
lock tables t1 read;
unlock tables;
lock tables t1 read;
update t1 set n = 3;
unlock tables;
show status like 'Table_lock%';
Variable_name	Value
Table_locks_immediate	3
Table_locks_waited	1
drop table t1;
select 1;
1
1
show status like 'last_query_cost';
Variable_name	Value
Last_query_cost	0.000000
FLUSH STATUS;
SHOW STATUS LIKE 'max_used_connections';
Variable_name	Value
Max_used_connections	1
SET @save_thread_cache_size=@@thread_cache_size;
SET GLOBAL thread_cache_size=3;
SHOW STATUS LIKE 'max_used_connections';
Variable_name	Value
Max_used_connections	3
FLUSH STATUS;
SHOW STATUS LIKE 'max_used_connections';
Variable_name	Value
Max_used_connections	2
SHOW STATUS LIKE 'max_used_connections';
Variable_name	Value
Max_used_connections	3
SHOW STATUS LIKE 'max_used_connections';
Variable_name	Value
Max_used_connections	4
SET GLOBAL thread_cache_size=@save_thread_cache_size;