> For the complete documentation index, see [llms.txt](https://mariadb.com/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mariadb.com/docs/server/reference/sql-statements/data-definition.md).

# Data Definition (DDL)

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[Atomic DDL](/docs/server/reference/sql-statements/data-definition/atomic-ddl.md)
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Learn about crash-safe DDL operations in MariaDB. This feature ensures data definition statements are either fully committed or completely rolled back, preventing metadata inconsistency.
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[CONSTRAINT](/docs/server/reference/sql-statements/data-definition/constraint.md)
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Complete constraints reference: PRIMARY KEY, FOREIGN KEY, UNIQUE, and CHECK syntax in CREATE/ALTER TABLE, ON DELETE/UPDATE actions, TABLE\_CONSTRAINTS table.
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[RENAME TABLE](/docs/server/reference/sql-statements/data-definition/rename-table.md)
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Change the name of one or more tables atomically. This command moves tables within or between databases while preserving their data and structure.
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[Renaming Databases](/docs/server/reference/sql-statements/data-definition/renaming-databases.md)
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Learn the supported methods for renaming a database. Since RENAME DATABASE is not available, this guide outlines safe workarounds like dumping and reloading or moving tables.
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[ALTER](/docs/server/reference/sql-statements/data-definition/alter.md)
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Access the reference for ALTER statements. This section lists commands to modify existing database objects, including tables, databases, users, and servers.
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[CREATE](/docs/server/reference/sql-statements/data-definition/create.md)
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Explore the CREATE statements used to define new database objects. This guide covers syntax for creating databases, tables, indexes, views, and stored routines.
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[DROP](/docs/server/reference/sql-statements/data-definition/drop.md)
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Find statements to remove database objects. This section details the syntax for deleting databases, tables, users, and other entities when they are no longer needed.
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