2 MySQL 常用命令

1 显示所有数据库: show databases

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
4 rows in set (0.06 sec)

information_schema // 提供了源数据信息,如:数据库名;表名;字段名
mysql // 存储用户权限信息,及帮助信息
performance_schema // 服务器性能相关数据,性能参数等
sys // 服务器运行信息

2 使用数据库: use <数据库名>

mysql> use mysql
Database changed

3 显示/查询当前数据库: select database();

mysql> select database();
+------------+
| database() |
+------------+
| mysql      |
+------------+
1 row in set (0.00 sec)

4 显示/查询当前数据库版本: select version();

mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.18    |
+-----------+
1 row in set (0.00 sec)

5 显示/查询数据库系统时间: select now();

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2019-11-24 23:27:40 |
+---------------------+
1 row in set (0.00 sec)

6 显示/查询用户: select user();

mysql> select user();
+----------------+
| user()         |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)