使用select和show命令查看mysql数据库系统信息

(1).select

　　显示当前日期和时间

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2019-06-05 13:46:20 |
+---------------------+
1 row in set (0.00 sec)

　　显示当前日期

mysql> select curdate();
+------------+
| curdate()  |
+------------+
| 2019-06-05 |
+------------+
1 row in set (0.04 sec)

　　显示当前时间

mysql> select curtime();
+-----------+
| curtime() |
+-----------+
| 13:48:15  |
+-----------+
1 row in set (0.00 sec)

　　显示当前所在数据库

mysql> use test_db;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
 
Database changed
mysql> select database();
+------------+
| database() |
+------------+
| test_db    |
+------------+
1 row in set (0.00 sec)

　　显示Mysql版本

mysql> select version(); 
+-----------+
| version() |
+-----------+
| 5.7.16    |
+-----------+
1 row in set (0.00 sec)

　　显示当前用户

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

(2).show

　　show variables;显示变量

　　show global variables;显示全局变量

　　show global variables like '%version%';显示版本信息

mysql> show global variables like '%version%';
+-------------------------+------------------------------+
| Variable_name           | Value                        |
+-------------------------+------------------------------+
| innodb_version          | 5.7.16                       |
| protocol_version        | 10                           |
| slave_type_conversions  |                              |
| tls_version             | TLSv1,TLSv1.1                |
| version                 | 5.7.16                       |
| version_comment         | MySQL Community Server (GPL) |
| version_compile_machine | x86_64                       |
| version_compile_os      | Linux                        |
+-------------------------+------------------------------+
8 rows in set (0.00 sec)

　　 show variables like '%storage_engine%';显示默认的存储引擎

mysql> show variables like '%storage_engine%'; 
+----------------------------------+--------+
| Variable_name                    | Value  |
+----------------------------------+--------+
| default_storage_engine           | InnoDB |
| default_tmp_storage_engine       | InnoDB |
| disabled_storage_engines         |        |
| internal_tmp_disk_storage_engine | InnoDB |
+----------------------------------+--------+
4 rows in set (0.00 sec)