0x00 查询MySql安装路径

select @@basedir;

mysql> select @@basedir;
+--------------------------------+
| @@basedir                      |
+--------------------------------+
| D:/phpStudy/PHPTutorial/MySQL/ |
+--------------------------------+
1 row in set (0.00 sec)

0x01 查询当前连接数据库

select database();

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

0x02 查询用户

select user();

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

select current_user;

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

select current_user();

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

select system_user();

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

select SESSION_USER();

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

0x03 查询当前连接的数据库版本

select version();

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.5.53    |
+-----------+
1 row in set (0.00 sec)

select @@version;

mysql> select @@version;
+-----------+
| @@version |
+-----------+
| 5.5.53    |
+-----------+
1 row in set (0.00 sec)

0x04 文件读取最大值

select @@max_allowed_packet;

mysql> select @@max_allowed_packet;
+----------------------+
| @@max_allowed_packet |
+----------------------+
|              1048576 |
+----------------------+
1 row in set (0.00 sec)