Spark SQL ガイド

DESCRIBE DATABASE

説明

​ DESCRIBE DATABASE ステートメントは、既存のデータベースのメタデータを返します。メタデータ情報には、データベース名、データベースコメント、およびファイルシステム上のデータベースの場所が含まれます。オプションの EXTENDED オプションが指定されている場合、基本メタデータ情報とデータベースプロパティが返されます。 DATABASE と SCHEMA は相互に交換可能です。

構文

{ DESC | DESCRIBE } DATABASE [ EXTENDED ] db_name

パラメータ

例

-- Create employees DATABASE
CREATE DATABASE employees COMMENT 'For software companies';

-- Describe employees DATABASE.
-- Returns Database Name, Description and Root location of the filesystem
-- for the employees DATABASE.
DESCRIBE DATABASE employees;
+-------------------------+-----------------------------+
|database_description_item|   database_description_value|
+-------------------------+-----------------------------+
|            Database Name|                    employees|
|              Description|       For software companies|
|                 Location|file:/Users/Temp/employees.db|
+-------------------------+-----------------------------+

-- Create employees DATABASE
CREATE DATABASE employees COMMENT 'For software companies';

-- Alter employees database to set DBPROPERTIES
ALTER DATABASE employees SET DBPROPERTIES ('Create-by' = 'Kevin', 'Create-date' = '09/01/2019');

-- Describe employees DATABASE with EXTENDED option to return additional database properties
DESCRIBE DATABASE EXTENDED employees;
+-------------------------+---------------------------------------------+
|database_description_item|                   database_description_value|
+-------------------------+---------------------------------------------+
|            Database Name|                                    employees|
|              Description|                       For software companies|
|                 Location|                file:/Users/Temp/employees.db|
|               Properties|((Create-by,kevin), (Create-date,09/01/2019))|
+-------------------------+---------------------------------------------+

-- Create deployment SCHEMA
CREATE SCHEMA deployment COMMENT 'Deployment environment';

-- Describe deployment, the DATABASE and SCHEMA are interchangeable, their meaning are the same.
DESC DATABASE deployment;
+-------------------------+------------------------------+
|database_description_item|database_description_value    |
+-------------------------+------------------------------+
|            Database Name|                    deployment|
|              Description|        Deployment environment|
|                 Location|file:/Users/Temp/deployment.db|
+-------------------------+------------------------------+