mysql升级是经常要做的工作，整理下升级步骤（物理升级）
1，关闭mysql服务
2，高版本软件覆盖低版本软件（替换掉basedir）
3，赋予新的高版本软件mysql权限
4，使用新的软件开启数据库
5，执行mysql_upgrade升级
实验：
5.6.23升级到5.7.12
1，关闭正在运行的mysql5.6.23的服务
2，删除低版本的mysql软件（basedir）
[root@mysqlupgrade mysql]# rm -rf mysql/
3，解压高版本的mysql软件包，覆盖到原来的位置
[root@mysqlupgrade soft]# tar xzvf mysql-5.7.12-linux-glibc2.5-x86_64.tar.gz -C /data/mysql/
[root@mysqlupgrade mysql]# mv mysql-5.7.12-linux-glibc2.5-x86_64 mysql
4，赋予权限
[root@mysqlupgrade mysql]# chown -R mysql:mysql mysql/
5，开启数据库
[root@mysqlupgrade mysql]# bin/mysqld_safe --ledir=/data/mysql/mysql/bin --user=mysql &
6，进入数据库，查看当前版本
mysql> select version();
+-----------+
| version() |
+-----------+
| 5.7.12 |
+-----------+
1 row in set (0.00 sec)
6，mysql_upgrade升级
[root@mysqlupgrade mysql]# bin/mysql_upgrade -udbauser -p123456 -h292.168.56.99 -P3306
mysql_upgrade: [Warning] Using a password on the command line interface can be insecure.
Checking if update is needed.
Checking server version.
Running queries to upgrade MySQL server.
Checking system database.
mysql.columns_priv OK
mysql.db OK
mysql.engine_cost OK
mysql.event OK
mysql.func OK
mysql.general_log OK
mysql.gtid_executed OK
mysql.help_category OK
mysql.help_keyword OK
mysql.help_relation OK
mysql.help_topic OK
mysql.innodb_index_stats OK
mysql.innodb_table_stats OK
mysql.ndb_binlog_index OK
mysql.plugin OK
mysql.proc OK
mysql.procs_priv OK
mysql.proxies_priv OK
mysql.server_cost OK
mysql.servers OK
mysql.slave_master_info OK
mysql.slave_relay_log_info OK
mysql.slave_worker_info OK
mysql.slow_log OK
mysql.tables_priv OK
mysql.time_zone OK
mysql.time_zone_leap_second OK
mysql.time_zone_name OK
mysql.time_zone_transition OK
mysql.time_zone_transition_type OK
mysql.user OK
Upgrading the sys schema.
Checking databases.
sys.sys_config OK
Upgrade process completed successfully.
Checking if update is needed.
[root@mysqlupgrade mysql]#

备注：
升级的时候报错
[root@mysqlupgrade mysql]# /data/mysql/mysql/bin/mysql_upgrade -udbauser -p123456
Warning: Using a password on the command line interface can be insecure.
Looking for 'mysql' as: /data/mysql/mysql/bin/mysql
Looking for 'mysqlcheck' as: /data/mysql/mysql/bin/mysqlcheck
Error: Failed while fetching Server version! Could be due to unauthorized access.
FATAL ERROR: Upgrade failed

mysql -udbauser -p123abc456 -h292.168.56.99 -P3306
测试下这样 是否可以连上，必须要能连上才可以。