## 一、查詢數據庫
### 1.展示系統中當前所有數據庫：`show databases;`
例：
```sql
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| school |
| school_01 |
| shop |
| sys |
+--------------------+
7 rows in set (0.00 sec)
```
### 2.查詢數據庫的創建信息：`show create database db_name;`
例，查詢數據庫 school 和 mysql 的創建信息：
```sql
mysql> show create database school;
+----------+----------------------------------------------------------------------------------+
| Database | Create Database |
+----------+----------------------------------------------------------------------------------+
| school | CREATE DATABASE `school` /*!40100 DEFAULT CHARACTER SET utf8 COLLATE utf8_bin */ |
+----------+----------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> show create database mysql;
+----------+------------------------------------------------------------------+
| Database | Create Database |
+----------+------------------------------------------------------------------+
| mysql | CREATE DATABASE `mysql` /*!40100 DEFAULT CHARACTER SET latin1 */ |
+----------+------------------------------------------------------------------+
1 row in set (0.00 sec)
```
## 二、查詢表
## 三、查詢信息
### 1.查詢給出的警告信息 `show warnings;`
例：
```sql
mysql> create database if not exists test2;
Query OK, 1 row affected, 1 warning (0.00 sec)
mysql> show warnings;
+-------+------+------------------------------------------------+
| Level | Code | Message |
+-------+------+------------------------------------------------+
| Note | 1007 | Can't create database 'test2'; database exists |
+-------+------+------------------------------------------------+
1 row in set (0.00 sec)
```
