Mysql 数据库创建与删除(基础2)

pyvip@Vip:~$ mysql -uxlong -pqwe123         #使用普通用户登录Mysql
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.7.21-0ubuntu0.16.04.1 (Ubuntu)

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owners.

Type ‘help;‘ or ‘\h‘ for help. Type ‘\c‘ to clear the current input statement.

mysql> create database mybd1;    #创建一个名为 "mydb1" 的数据库
Query OK, 1 row affected (0.00 sec)

mysql> show databases;             #查看创建的数据库 "mydb1"
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mybd1              |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

mysql> drop database mybd1;    #删除名为 "mydb1" 的数据库，也可以使用这样语法删除数据库（drop database if exists  mydb1;）
Query OK, 0 rows affected (0.00 sec)

mysql> show databases;    #查看删除结果， "mydb1" 数据库已经被删除了
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.00 sec)

mysql> SELECT DATABASE();  #查看当前在数据库的目录，类似linux中的pwd。 
+------------+             #这个结果表示，当前只是在mysql大厅里面，还没有进入数据库中。
| DATABASE() |
+------------+
| NULL       |
+------------+
1 row in set (0.01 sec)      

mysql> create database mydb123;    #创建一个数据库
Query OK, 1 row affected (0.00 sec)

mysql> show databases;     #查看创建结果，mydb123 已经创建完成
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mydb123            |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

mysql> use mydb123;    #进入创建的mydb123 数据库
Database changed
mysql> select database();  #查看当前所在数据库目录，已经进入mydb123 数据库。
+------------+
| database() |
+------------+
| mydb123    |
+------------+
1 row in set (0.00 sec)

mysql>