Data Definition Language (DDL)

The Data Definition Language (DDL) manages table and index structure. The most basic items of DDL are the CREATE, ALTER, RENAME and DROP statements:

• CREATE creates an object (a table, for example) in the
• DROP deletes an object in the database, usually
• ALTER modifies the structure an existing object in various ways—for example, adding a column to an existing

Data Manipulation Language (DML)

The Data Manipulation Language (DML) is the subset of SQL used to add, update and delete data.

The acronym CRUD refers to all of the major functions that need to be implemented in a relational database application to consider it complete. Each letter in the acronym can be mapped to a standard SQL statement: