查看所有数据库

show databases;

切换数据库

# 切换到student数据库
use student;

查看当前数据库

select database();

或 通过show tables查看
mysql> show tables;
+-----------------+
| Tables_in_alpha |
+-----------------+
| author          |
| author2book     |
| author2book2    |
| book            |
| customer        |
| department      |
| employee        |
| student         |
+-----------------+
8 rows in set (0.04 sec)

或 通过status查看
mysql> status;
--------------
mysql  Ver 8.0.18 for osx10.15 on x86_64 (Homebrew)

Connection id:        12
Current database:    alpha
Current user:        root@localhost
SSL:            Not in use
Current pager:        less
Using outfile:        ''
Using delimiter:    ;
Server version:        8.0.18 Homebrew
Protocol version:    10
Connection:        Localhost via UNIX socket
Server characterset:    utf8mb4
Db     characterset:    utf8mb4
Client characterset:    utf8mb4
Conn.  characterset:    utf8mb4
UNIX socket:        /tmp/mysql.sock
Uptime:            4 days 20 hours 19 min 58 sec

查看当前数据库包含的表

show tables;