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总结一下MySQL跨库访问的方法：
类DB-Link方法 Oracle实现跨库访问非常简单，因为有现成的db-link可用，MySQL虽然没有DB-Link，但使用特殊的存储引擎“FEDERATED”就可以实现同样的功能。具体操作如下：
# 登录本地MySQL（使用端口为3338的实例做示例）
mysql -uroot -p -h 127.0.0.1 -P 3338
-- 查看“FEDERATED”引擎是否启用(Support)
MySQL [(none)]> show engines;
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| InnoDB | DEFAULT | Percona-XtraDB, Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)
-- 这里的Support=NO，说明MySQL启动时没有加载，需要在配置文件内配置加载，重启MySQL生效。
MySQL [(none)]> exit
Bye
# 修改my.ini文件，添加 federated = ON 后保存退出，重启MySQL
# 进入MySQL确认 federated引擎 已启动
mysql -uroot -p -h 127.0.0.1 -P 3338
MySQL [(none)]> show engines;
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO |
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO |
| MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO |
| InnoDB | DEFAULT | Percona-XtraDB, Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| FEDERATED | YES | Federated MySQL storage engine | NO | NO | NO |
+--------------------+---------+----------------------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)
-- 建立远端Server |