您可以通過SHOW
語句查看資料庫相關資訊,例如資料庫列表、資料庫中的表以及表中的列或索引等。
SHOW DATABASES
查看當前叢集中的資料庫。
文法
SHOW DATABASES;
樣本
SHOW DATABASES;
返回結果如下:
+--------------------+
| Database |
+--------------------+
| adb_test |
| MYSQL |
| adb_demo |
| INFORMATION_SCHEMA |
+--------------------+
SHOW TABLES
查看使用者當前資料庫中的表。
文法
SHOW TABLES [IN db_name];
樣本
SHOW TABLES IN adb_demo;
返回結果如下:
+--------------------+
| Tables_in_adb_demo |
+--------------------+
| customer |
| json_test |
+--------------------+
SHOW COLUMNS
查看錶的列資訊。
文法
SHOW COLUMNS IN db_name.table_name;
樣本
SHOW COLUMNS IN adb_demo.customer;
返回結果如下:
+---------+---------+------+------+---------+-------+
| 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
查看錶的建表語句。
文法
SHOW CREATE TABLE db_name.table_name;
樣本
SHOW CREATE TABLE adb_demo.customer;
返回結果如下:
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| customer | Create Table `customer` (
`id` int NOT NULL,
`name` varchar(50),
`address` varchar(80),
`gender` boolean,
primary key (`id`)
) DISTRIBUTED BY HASH(`id`) INDEX_ALL='Y' STORAGE_POLICY='HOT' BLOCK_SIZE=8192 |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
SHOW GRANTS
查看使用者的許可權。
文法
SHOW GRANTS [FOR 'username'@'hostname'];
其中,username
為使用者名稱,hostname
為主機名稱或主機IP。
樣本
查看目前使用者的許可權,無需指定使用者名稱和主機。
SHOW GRANTS;
返回結果如下:
+---------------------------------------------------------+ | Grants for adb_acc@% | +---------------------------------------------------------+ | GRANT ALL ON `*`.`*` TO 'adb_acc'@'%' WITH GRANT OPTION | +---------------------------------------------------------+
查看指定使用者的許可權。
SHOW GRANTS FOR 'test'@'%';
返回結果如下:
+---------------------------------------------------------+ | Grants for test@% | +---------------------------------------------------------+ | GRANT ALL ON `*`.`*` TO 'adb'@'%' WITH GRANT OPTION | +---------------------------------------------------------+
SHOW INDEXES
查看錶的索引資訊。
文法
SHOW INDEXES FROM db_name.table_name;
樣本
SHOW INDEXES FROM adb_demo.json_test;
返回結果如下,其中Key_name
即為索引名:
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+
| 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 | | |
+-----------+------------+----------+--------------+-------------+-----------+-------------+----------+--------+------+------------+---------+---------------+