MySql DDL

DDL :  Data Definition Language

用途：

        用于描述数据库中存储的现实世界实体的语言。即创建数据库和表的结构。

CREATE  ALTER  DROP TRUNCATE  

CREATE  {DATABASE | SCHEMA }  [ IF NOT EXISTS ]  数据库名称

 CREATE DATABASE IF NOT EXISTS mydb3 CHARACTER SET utf8 COLLATE utf8_general_ci；

mysql> SHOW CREATE DATABASE mydb1;

+----------+----------------------------------------------------------------+

| Database | Create Database                                                |

+----------+----------------------------------------------------------------+

| mydb1    | CREATE DATABASE `mydb1` /*!40100 DEFAULT CHARACTER SET utf8 */ |

+----------+----------------------------------------------------------------+

1 row in set (0.00 sec)

mysql>

mysql>

mysql>

mysql>

mysql> SHOW CREATE DATABASE mydb2;

+----------+---------------------------------------------------------------+

| Database | Create Database                                               |

+----------+---------------------------------------------------------------+

| mydb2    | CREATE DATABASE `mydb2` /*!40100 DEFAULT CHARACTER SET gbk */ |

+----------+---------------------------------------------------------------+

1 row in set (0.00 sec)

mysql> SHOW CREATE DATABASE mydb3;

+----------+----------------------------------------------------------------+

| Database | Create Database                                                |

+----------+----------------------------------------------------------------+

| mydb3    | CREATE DATABASE `mydb3` /*!40100 DEFAULT CHARACTER SET utf8 */ |

+----------+----------------------------------------------------------------+

1 row in set (0.00 sec)

查询

SHOW DATABASES;

SHOW CREATE DATABASE 数据库名称；

删除

DROP DATABASE 数据库名称；

mysql> SHOW CREATE DATABASE mydb3;

+----------+----------------------------------------------------------------+

| Database | Create Database                                                |

+----------+----------------------------------------------------------------+

| mydb3    | CREATE DATABASE `mydb3` /*!40100 DEFAULT CHARACTER SET utf8 */ |

+----------+----------------------------------------------------------------+

1 row in set (0.00 sec)

mysql> DROP DATABASE IF EXISTS mydb3;

Query OK, 0 rows affected (0.02 sec)

mysql> SHOW DATABASES;

+--------------------+

| Database           |

+--------------------+

| information_schema |

| mydb1              |

| mydb2              |

| mysql              |

| test               |

+--------------------+

5 rows in set (0.00 sec)

修改

ALERT

mysql> SHOW CREATE DATABASE mydb1;

+----------+----------------------------------------------------------------+

| Database | Create Database                                                |

+----------+----------------------------------------------------------------+

| mydb1    | CREATE DATABASE `mydb1` /*!40100 DEFAULT CHARACTER SET utf8 */ |

+----------+----------------------------------------------------------------+

1 row in set (0.00 sec)

mysql> ALTER DATABASE mydb2 CHARACTER SET utf8;

Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE DATABASE mydb2;

+----------+----------------------------------------------------------------+

| Database | Create Database                                                |

+----------+----------------------------------------------------------------+

| mydb2    | CREATE DATABASE `mydb2` /*!40100 DEFAULT CHARACTER SET utf8 */ |

+----------+----------------------------------------------------------------+

1 row in set (0.00 sec)