一 、创建数据库
1.通过CREATE DATABASE db_library;创建名称为db_library的数据库。
2.通过CREATE SCHEMA db_library1;创建名称为db_library1的数据库。
3.通过mysql> CREATE DATABASE db_library_gbk -> CHARACTER SET = GBK;指定其字符集为GBK。
4.通过CREATE DATABASE IF NOT EXISTS db_library2;判断该数据库名称是否存在，只有在不存在时才创建。
二、查看数据库
1.使用SHOW DATABASES;语句查看Mysql服务器中所有数据库名称。
mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | db_database13 | | db_library | | db_library1 | | db_library2 | | db_library_gbk | | hotel | | mybatis | | mysql | | mysqldb | | performance_schema | | se | | spring | | springapp | | sys | | test | +--------------------+ 16 rows in set (0.01 sec)
三、选择名称为db_library的数据库，设置其为当前默认的数据库
mysql> USE db_library; Database changed
四、修改数据库db_library1，设置默认字符集为GBK和校对规则为简体中文
mysql> ALTER DATABASES db_library1
-> DEFAULT CHARACTER SET gbk
-> DEFAULT CHARACTER SET gbk^C
mysql> ALTER DATABASE db_library1
-> DEFAULT CHARACTER SET gbk
-> DEFAULT COLLATE gbk_chinese_ci;
Query OK, 1 row affected (0.00 sec)
五、删除数据库
mysql> DROP DATABASE db_library2; Query OK, 0 rows affected (0.01 sec) mysql> SHOW DATABASES; +--------------------+ | Database | +--------------------+ | information_schema | | db_database13 | | db_library | | db_library1 | | db_library_gbk | | hotel | | mybatis | | mysql | | mysqldb | | performance_schema | | se | | spring | | springapp | | sys | | test | +--------------------+ 15 rows in set (0.00 sec)
六、数据库存储引擎
存储引擎其实就是存储数据，为存储的数据建立索引，以及更新、查询数据等技术的实现方法。因为在关系数据库中数据是以表的形式存储的，所以存储引擎也可以成为表类型。
1.查询支持的全部存储引擎
mysql> SHOW ENGINES G
*************************** 1. row ***************************
Engine: InnoDB
Support: DEFAULT
Comment: Supports transactions, row-level locking, and foreign keys
Transactions: YES
XA: YES
Savepoints: YES
*************************** 2. row ***************************
Engine: MRG_MYISAM
Support: YES
Comment: Collection of identical MyISAM tables
Transactions: NO
XA: NO
Savepoints: NO
*************************** 3. row ***************************
Engine: MEMORY
Support: YES
Comment: Hash based, stored in memory, useful for temporary tables
Transactions: NO
XA: NO
Savepoints: NO
*************************** 4. row ***************************
Engine: BLACKHOLE
Support: YES
Comment: /dev/null storage engine (anything you write to it disappears)
Transactions: NO
XA: NO
Savepoints: NO
*************************** 5. row ***************************
Engine: MyISAM
Support: YES
Comment: MyISAM storage engine
Transactions: NO
XA: NO
Savepoints: NO
*************************** 6. row ***************************
Engine: CSV
Support: YES
Comment: CSV storage engine
Transactions: NO
XA: NO
Savepoints: NO
*************************** 7. row ***************************
Engine: ARCHIVE
Support: YES
Comment: Archive storage engine
Transactions: NO
XA: NO
Savepoints: NO
*************************** 8. row ***************************
Engine: PERFORMANCE_SCHEMA
Support: YES
Comment: Performance Schema
Transactions: NO
XA: NO
Savepoints: NO
*************************** 9. row ***************************
Engine: FEDERATED
Support: NO
Comment: Federated MySQL storage engine
Transactions: NULL
XA: NULL
Savepoints: NULL
9 rows in set (0.00 sec)
2.查询默认的存储引擎，为InnoDB。
mysql> SHOW VARIABLES LIKE '%storage_engine%'; +----------------------------------+--------+ | Variable_name | Value | +----------------------------------+--------+ | default_storage_engine | InnoDB | | default_tmp_storage_engine | InnoDB | | disabled_storage_engines | | | internal_tmp_disk_storage_engine | InnoDB | +----------------------------------+--------+ 4 rows in set, 1 warning (0.01 sec)
3.InnoDB存储引擎
优势在于提供了良好的事务管理、崩溃修复能力和并发控制。缺点是其读写速率稍差，占用的数据空间比较大。
4.MylSAM存储引擎
优势在于占用空间小，处理速度快。缺点是不支持事务的完整性和并发性。
5.MEMORY存储引擎
大小受限，其存在于内存中的特性使得这类表的处理速度非常快，但是其数据易丢失，声明周期短。