DDL stands for Data Definition Language. It refers to a category of SQL (Structured Query Language) statements that are used to define and manage the structure or schema of a database. DDL statements are primarily concerned with creating, altering, or dropping database objects like tables, indexes, views, and constraints.
In essence, DDL provides a means for database administrators or developers to define the logical and physical structures of a database system. Key DDL statements include:
1. CREATE: This statement is used to create new objects like tables, indexes, views, or constraints in a database.
2. ALTER: It is employed to modify the structure or properties of existing database objects, such as adding or dropping columns, modifying constraints, or renaming objects.
3. DROP: This statement allows for the removal or deletion of database objects, like dropping a table or index.
4. TRUNCATE: It is used to remove all rows from a table, effectively resetting it to its initial state.
DDL statements are typically executed by database administrators or developers using specialized tools or directly through command-line interfaces. These statements play a crucial role in defining the overall structure of the database system, ensuring data integrity, and facilitating efficient data retrieval and manipulation.
