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

查看当前登录用户的权限。

  • 语法
    SHOW GRANTS;
  • 示例
    SHOW GRANTS;
    返回结果如下：
    +---------------------------------------------------------+
| Grants for adb_acc@%                                    |
+---------------------------------------------------------+
| GRANT ALL ON `*`.`*` TO 'adb_acc'@'%' 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      |         |               |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+