###查看用户
SELECT DISTINCT CONCAT('User: ''',user,'''@''',host,''';') AS query FROM mysql.user;
###查看数据库运行时间
show global status like 'uptime';
##数据库已使用连接数
show global status like 'Max_used_connections';
+----------------------+-------+
| Variable_name | Value |
+----------------------+-------+
| Max_used_connections | 170 |
+----------------------+-------+
###最大连接数
show variables like 'max_connections';
+-----------------+-------+
| Variable_name | Value |
+-----------------+-------+
| max_connections | 4096 |
+-----------------+-------+
#####mysqldump 备份数据库（逻辑备份）
mysqldump -uroot -p --single-transaction --routines --flush-logs --flush-privileges --all-databases > /tmp/alldbbak.sql
mysqldump -uroot -p --single-transaction --master-data=2 --routines --flush-logs --flush-privileges --all-databases > /tmp/alldbbak.sql