<a id="flink-sql-statements-overview"></a>

# DDL Statements in Confluent Cloud for Apache Flink

In Confluent Cloud for Apache Flink®, a [statement](../../concepts/statements.md#flink-sql-statements) is a high-level
resource that’s created when you enter a SQL query.

Data Definition Language (DDL) statements are imperative verbs that define
metadata in Flink SQL by adding, changing, or deleting tables.

Unlike queries, which include Data Query Language (DQL) statements such as
`SELECT` and Data Manipulation Language (DML) statements such as
`INSERT INTO`, DDL statements modify only metadata and don’t change data.
When you want to change data, use [queries](../queries/overview.md#flink-sql-queries).

For valid lexical structure of statements, see [Flink SQL Syntax in Confluent Cloud for Apache Flink](../sql-syntax.md#flink-sql-syntax).

## Available DDL statements

These are the available DDL statements in Confluent Cloud for Flink SQL.

ALTER
: - [ALTER MATERIALIZED TABLE](alter-materialized-table.md#flink-sql-alter-materialized-table):
    Change properties of an existing materialized table or evolve its query.
  - [ALTER TABLE](alter-table.md#flink-sql-alter-table): Change properties of an
    existing table.
  - [ALTER MODEL](alter-model.md#flink-sql-alter-model): Rename an
    [AI model](../../../ai/overview.md#ai-overview) or change model options.
  - [ALTER AGENT](alter-agent.md#flink-sql-alter-agent): Modify agent configuration.

CREATE
: - [CREATE MATERIALIZED TABLE](create-materialized-table.md#flink-sql-create-materialized-table):
    Create a persistent streaming pipeline backed by a Apache Kafka® topic.
  - [CREATE OR ALTER MATERIALIZED TABLE](create-or-alter-materialized-table.md#flink-sql-create-or-alter-materialized-table):
    Create or evolve a materialized table in a single statement.
  - [CREATE TABLE](create-table.md#flink-sql-create-table): Register a table into the
    current or specified catalog (Confluent Cloud environment).
  - [CREATE FUNCTION](create-function.md#flink-sql-create-function): Register a user-defined
    function (UDF) in the current database (Apache Kafka® cluster).
  - [CREATE MODEL](create-model.md#flink-sql-create-model): Create a new AI model.
  - [CREATE AGENT](create-agent.md#flink-sql-create-agent): Create a new Streaming Agent.

DESCRIBE
: - [DESCRIBE](describe.md#flink-sql-describe): Show properties of a table, AI model,
    or UDF.

DROP
: - [DROP MATERIALIZED TABLE](drop-materialized-table.md#flink-sql-drop-materialized-table): Remove a
    materialized table and its backing Kafka topic.
  - [DROP MODEL](drop-model.md#flink-sql-drop-model): Remove an AI model.
  - [DROP TABLE](drop-table.md#flink-sql-drop-table): Remove a table.
  - [DROP VIEW](drop-view.md#flink-sql-drop-view): Remove a view from a catalog.
  - [DROP AGENT](drop-agent.md#flink-sql-drop-agent): Remove an agent.

EXPLAIN
: - [EXPLAIN](explain.md#flink-sql-explain): View the query plan of a Flink SQL
    statement.

RESET
: - [RESET](reset.md#flink-sql-reset-statement): Reset the Flink SQL shell
    configuration to default settings.

SET
: - [SET](set.md#flink-sql-set-statement): Modify or list the Flink SQL shell
    configuration.

SHOW
: - [SHOW CATALOGS](show.md#flink-sql-show-catalogs): List all catalogs.
  - [SHOW CREATE MODEL](show.md#flink-sql-show-create-model): Show details about
    an AI inference model.
  - [SHOW CREATE MATERIALIZED TABLE](show.md#flink-sql-show-create-materialized-table):
    Show details about a materialized table.
  - [SHOW CREATE TABLE](show.md#flink-sql-show-create-table): Show details about
    a table.
  - [SHOW CURRENT CATALOG](show.md#flink-sql-show-current-catalog): Show the
    current catalog.
  - [SHOW CURRENT DATABASE](show.md#flink-sql-show-current-database): Show the
    current database.
  - [SHOW DATABASES](show.md#flink-sql-show-databases): List all databases in the
    current catalog.
  - [SHOW FUNCTIONS](show.md#flink-sql-show-functions): List all functions in the
    current catalog and database.
  - [SHOW JOBS](show.md#flink-sql-show-jobs): List the status of all statements
    in the current catalog.
  - [SHOW MODELS](show.md#flink-sql-show-models): List all AI models that are
    registered in the current catalog.
  - [SHOW TABLES](show.md#flink-sql-show-tables): List all tables for the current
    database.
  - [SHOW AGENTS](show.md#flink-sql-show-agents): List all agents in the current environment.

USE
: - [USE CATALOG](use-catalog.md#flink-sql-use-catalog-statement): Set the current
    catalog.
  - [USE [database_name]](use-database.md#flink-sql-use-database-statement): Set the
    current database.

## Related content

- [Flink SQL Syntax](../sql-syntax.md#flink-sql-syntax)
- [Flink SQL Queries](../queries/overview.md#flink-sql-queries)
- [Stream Processing Concepts](../../concepts/overview.md#flink-sql-stream-processing-concepts)
- [Built-in Functions](../functions/overview.md#flink-sql-functions-overview)

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