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# Data Definition Language (DDL) Statement Reference

> Access Data Definition Language command reference for creating and managing database structures.

DDL statements allow users to run commands and administrative operations on the Ocient® System. You can execute DDL statements over a database connection to manage nodes, storage spaces, tables and views, system configuration, users and groups, underlying storage segments, and more.

> **Warning**
>
> **Quoting Identifiers**
>
> In all DDL statements, identifiers not in double quotes must begin with a letter and can only contain letters, numbers, and underscores. Identifiers are the names of databases, tables, nodes, and so on. For details, see [**Identifiers**](/guides/query-ocient/general-sql-syntax/identifiers). The Ocient System internally converts identifiers to lower-case. Identifiers in double quotes can contain any characters besides newline and carriage return, can begin with any character, and are not case-adjusted. To use an identifier with the same name as any keyword, it must be in double quotes.
>
> String literals must be enclosed in single quotes. A single quote within a string can be escaped as "*.*A string literal can be preceded by e to enable additional escape sequences (for example: `e'\n'`).

DDL statements are supported for these categories:

## [**Cluster and Node Management**](/guides/sql-reference/data-definition-language-ddl-statement-reference/cluster-and-node-management)

* **CLUSTER**
  * CREATE CLUSTER
  * DROP CLUSTER
  * ALTER CLUSTER
    * ALTER CLUSTER ADD PARTICIPANTS
    * ALTER CLUSTER DROP PARTICIPANTS
    * ALTER CLUSTER ALTER CONFIG SET
    * ALTER CLUSTER ALTER LOG LEVEL SET
    * ALTER CLUSTER RENAME
* **STORAGESPACE**
  * CREATE STORAGESPACE
  * DROP STORAGESPACE
  * ALTER STORAGESPACE RENAME
* **NODE**
  * DROP NODE
  * ALTER NODE
    * ALTER NODE ADD ROLE
    * ALTER NODE REMOVE ROLE
    * ALTER NODE ALTER CONFIG SET
    * ALTER NODE RENAME
    * ALTER NODE ALTER LOG LEVEL SET
    * ALTER NODE ALTER METRIC LEVEL
    * ALTER NODE SET ADDRESS
* **CONNECTIVITY POOL**
  * CREATE CONNECTIVITY_POOL
  * DROP CONNECTIVITY_POOL
  * ALTER CONNECTIVITY_POOL
    * ALTER CONNECTIVITY_POOL SET
    * ALTER CONNECTIVITY_POOL RENAME TO
    * ALTER CONNECTIVITY_POOL ADD PARTICIPANTS
    * ALTER CONNECTIVITY_POOL ALTER PARTICIPANT
    * ALTER CONNECTIVITY_POOL DROP PARTICIPANTS
    * ALTER CONNECTIVITY_POOL SET SSO INTEGRATION
    * ALTER CONNECTIVITY_POOL REMOVE SSO INTEGRATION
* SSO INTEGRATION
  * CREATE SSO INTEGRATION
  * DROP SSO INTEGRATION
  * ALTER SSO INTEGRATION
* **SYSTEM**
  * ALTER SYSTEM ALTER CONFIG SET
  * ALTER SYSTEM RENAME TO
  * ALTER SYSTEM ALTER METRIC LEVEL
  * ALTER SYSTEM ALTER SECURITY

## [**Schemas**](/guides/sql-reference/data-definition-language-ddl-statement-reference/schemas)

* CREATE SCHEMA
* DROP SCHEMA
* ALTER SCHEMA RENAME

## [**Databases**](/guides/sql-reference/data-definition-language-ddl-statement-reference/databases)

* CREATE DATABASE
* DROP DATABASE
* ALTER DATABASE
  * ALTER DATABASE RENAME
  * ALTER DATABASE SET SSO INTEGRATION
  * ALTER DATABASE ALTER SSO INTEGRATION
  * ALTER DATABASE REMOVE SSO INTEGRATION
  * ALTER DATABASE ALTER SECURITY

## [**Tables**](/guides/sql-reference/data-definition-language-ddl-statement-reference/tables)

* CREATE TABLE
* CREATE TABLE AS SELECT (CTAS)
* CREATE TABLE AS SELECT USING LOADERS
* DROP TABLE
* ALTER TABLE
  * ALTER TABLE RENAME
  * ALTER TABLE RENAME COLUMN
  * ALTER TABLE ADD COLUMN
  * ALTER TABLE ALTER COLUMN COMPRESSION
  * ALTER TABLE ALTER REDUNDANCY
  * ALTER TABLE DROP COLUMN
  * ALTER TABLE STREAMLOADER_PROPERTIES
  * ALTER TABLE DISABLE INDEX
  * ALTER TABLE ENABLE INDEX
  * ALTER TABLE ENABLE RETENTION POLICY AGE
  * ALTER TABLE DISABLE RETENTION POLICY
* DELETE FROM TABLE
* EXPORT TABLE
* INSERT INTO TABLE
  * INSERT INTO TABLE USING LOADERS
* TRUNCATE TABLE

## [**Views**](/guides/sql-reference/data-definition-language-ddl-statement-reference/views)

* CREATE VIEW
* DROP VIEW
* ALTER VIEW RENAME
* ALTER VIEW AS
* EXPORT VIEW

## [**Indexes**](/guides/sql-reference/data-definition-language-ddl-statement-reference/indexes)

* CREATE INDEX
* DROP INDEX

## [**Data Pipelines**](/guides/sql-reference/data-definition-language-ddl-statement-reference/data-pipelines)

* PIPELINE
  * CREATE PIPELINE
  * DROP PIPELINE
  * PREVIEW PIPELINE
  * START PIPELINE
  * STOP PIPELINE
  * ALTER PIPELINE
  * ALTER PIPELINE RENAME
  * EXPORT PIPELINE
  * CREATE PIPELINE FUNCTION
  * DROP PIPELINE FUNCTION

## [**Distributed Tasks**](/guides/sql-reference/data-definition-language-ddl-statement-reference/distributed-tasks)

* **TASK**
  * CREATE TASK
  * CANCEL TASK

## [**Machine Learning Models**](/guides/sql-reference/data-definition-language-ddl-statement-reference/machine-learning-models)

* CREATE MLMODEL
* ALTER MLMODEL
* DROP MLMODEL
* EXPORT MLMODEL
* REFRESH MLMODEL

## [**Users, Groups, and Service Classes**](/guides/sql-reference/data-definition-language-ddl-statement-reference/users-groups-and-service-classes)

* **USER**
  * CREATE USER
  * DROP USER
  * ALTER USER
    * ALTER USER SET
* **GROUP**
  * CREATE GROUP
  * DROP GROUP
  * ALTER GROUP
    * ALTER GROUP USER
    * ALTER GROUP RENAME
    * ALTER GROUP SET SERVICE CLASS
    * ALTER GROUP ALTER SECURITY
* **SERVICE CLASS**
  * CREATE SERVICE CLASS
  * DROP SERVICE CLASS
  * ALTER SERVICE CLASS
    * ALTER SERVICE CLASS RENAME
    * ALTER SERVICE CLASS SET
    * ALTER SERVICE CLASS RESET
  * ALTER QUERY

## [**Data Integrity and Storage**](/guides/sql-reference/data-definition-language-ddl-statement-reference/data-integrity-and-storage)

* ALTER SEGMENT QUARANTINE

## [**Query Analysis**](/guides/sql-reference/data-definition-language-ddl-statement-reference/query-analysis)

* EXPLAIN
* EXPLAIN PIPELINE

## [**Query Management**](/guides/sql-reference/data-definition-language-ddl-statement-reference/query-management)

* CANCEL
* KILL

## [**Statistics Cache Management**](/guides/sql-reference/data-definition-language-ddl-statement-reference/statistics-cache-management)