您可以通过SHOW语句查看数据库相关信息，例如数据库列表、数据库中的表以及表中的列或索引等。
SHOW DATABASES
查看当前集群中的数据库。
语法
SHOW DATABASES; 示例
SHOW DATABASES;返回结果如下：
+--------------------+
| Database |
+--------------------+
| adb_test |
| MYSQL |
| adb_demo |
| INFORMATION_SCHEMA |
+--------------------+SHOW TABLES
查看用户当前数据库中的表。
语法
SHOW TABLES [IN db_name]; 示例
SHOW TABLES IN adb_demo;返回结果如下：
+--------------------+
| Tables_in_adb_demo |
+--------------------+
| customer |
| json_test |
+--------------------+SHOW COLUMNS
查看表的列信息。
语法
SHOW COLUMNS IN db_name.table_name； 示例
SHOW COLUMNS IN adb_demo.customer;返回结果如下：
+---------+---------+------+------+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+---------+------+------+---------+-------+
| id | int | NO | PRI | NULL | |
| name | varchar | YES | | NULL | |
| address | varchar | YES | | NULL | |
| gender | boolean | YES | | NULL | |
+---------+---------+------+------+---------+-------+SHOW CREATE TABLE
查看表的建表语句。
语法
SHOW CREATE TABLE db_name.table_name; 示例
SHOW CREATE TABLE adb_demo.customer;返回结果如下：
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| customer | Create Table `customer` (
`id` int NOT NULL,
`name` varchar(50),
`address` varchar(80),
`gender` boolean,
primary key (`id`)
) DISTRIBUTE BY HASH(`id`) INDEX_ALL='Y' STORAGE_POLICY='HOT' BLOCK_SIZE=8192 |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+SHOW GRANTS
查看用户的权限。
语法
SHOW GRANTS [FOR 'username'@'hostname'];其中，username为用户名，hostname为主机名或主机IP。
示例
- 查看当前用户的权限，无需指定用户名和主机。
返回结果如下：SHOW GRANTS;+---------------------------------------------------------+ | Grants for adb_acc@% | +---------------------------------------------------------+ | GRANT ALL ON `*`.`*` TO 'adb_acc'@'%' WITH GRANT OPTION | +---------------------------------------------------------+ - 查看指定用户的权限。
返回结果如下：SHOW GRANTS FOR 'test'@'%';+---------------------------------------------------------+ | Grants for test@% | +---------------------------------------------------------+ | GRANT ALL ON `*`.`*` TO 'adb'@'%' WITH GRANT OPTION | +---------------------------------------------------------+
SHOW INDEXES
查看表的索引信息。
语法
SHOW INDEXES FROM db_name.table_name; 示例
SHOW INDEXES FROM adb_demo.json_test;返回结果如下，其中
Key_name即为索引名：+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| Table | Non_unique | Key_name | Seq_in_index | Column_name | Collation | Cardinality | Sub_part | Packed | Null | Index_type | Comment | Index_comment |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| json_test | 1 | id_0_idx | 1 | id | A | 0 | NULL | NULL | | BTREE | | |
| json_test | 1 | vj_idx | 1 | vj | A | 0 | NULL | NULL | | BTREE | | |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+