如何查看当前的数据库与用户名

obclient> SELECT USER FROM DUAL;
+------+
| USER |
+------+
| SYS  |
+------+
1 row in set (0.00 sec)

obclient> SELECT database();
+------------+
| database() |
+------------+
| test       |
+------------+
1 row in set (0.00 sec)

obclient> SELECT user();
+---------------------+
| user()              |
+---------------------+
| root@xxx.xx.xxx.xxx |
+---------------------+
1 row in set (0.00 sec)