创建数据库
mysql> create database example;
Query OK, 1 row affected
查看已存在的数据库：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| MyCloudDB |
| example |
| mydatabase |
| mysql |
| performance_schema |
| sampledb |
| user_db |
+--------------------+
8 rows in set
删除数据库
mysql> drop database example;
Query OK, 0 rows affected
数据库存储引擎
查看支持的存储引擎
mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine | Support | Comment | Transactions | XA | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| MyISAM | YES | MyISAM storage engine | NO | NO | NO |
| CSV | YES | CSV storage engine | NO | NO | NO |
| MRG_MYISAM | YES | Collection of identical MyISAM tables | 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 |
| PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO |
| ARCHIVE | YES | Archive storage engine | NO | NO | NO |
| InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES |
| FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set
MyISAM和InnoDB存储引擎的区别
| MyISAM | InnoDB | |
| 构成 | 由表定义文件、数据文件和索引文件构成 | 由表空间数据文件和日志文件构成 |
| 事务 | 不支持 | 支持 |
| 操作 | SELECT操作性能更好 | INSERT和UPDATE性能更好 |
| 表的具体行数 |
select count(*) from table,MyISAM只要简单的读出保存好的行数， 注意的是，当count(*)语句包含 where条件时，两种表的操作是一样的 |
InnoDB 中不保存表的具体行数，也就是说，执行select count(*) from table时，InnoDB要扫描一遍整个表来计算有多少行 |
| 锁 | 表锁 |
提供行锁，提供不加锁读取，另外，InnoDB表的行锁也不是绝对的，如果在执行一个SQL语句时MySQL不能确定要扫描的范围，InnoDB表同样会锁全表，例如update table set num=1 where name like “%aaa%” |
InnoDB和Myisam区别点击这里。
查看默认存储引擎
mysql> show variables like 'storage_engine';
+----------------+--------+
| Variable_name | Value |
+----------------+--------+
| storage_engine | InnoDB |
+----------------+--------+
1 row in set