SQL Data Definition Language (DDL) consists of commands that shape and organize database structures. Essential for managing tables, schemas, and relationships in any data system.
The CREATE command is used to make new tables, databases, indexes, and views. It defines the structure and data types for all essential elements.
ALTER allows you to modify existing database structures add, update, or remove columns, and alter constraints without recreating the whole table from scratch.
The DROP command deletes entire tables, databases, or other objects. Use with caution, as this removes all data and associated structures permanently.
TRUNCATE removes all rows from a table but keeps the structure intact, making it different from DROP, which deletes both data and the table itself.
RENAME changes the name of a table or database object. This helps keep database names consistent and better aligned with evolving data models.
DDL commands help organize data, enforce rules, and ensure referential integrity with constraints supporting reliable, accurate, and maintainable databases.
Always back up data before DDL operations, review command syntax, and follow documentation. Careful use protects your data and maintains a stable database environment.