Which language is used for defining database structures?

The correct answer is DDL, which stands for Data Definition Language. DDL is a subset of SQL (Structured Query Language) specifically designed for defining and managing the structure of databases and their objects, such as tables, indexes, and schemas. It includes commands such as CREATE, ALTER, and DROP, which allow users to create new database structures, modify existing ones, or remove them entirely.

While SQL is the general language used for managing and querying databases, including both Data Definition Language (DDL) and Data Manipulation Language (DML), the specific question focuses on the subset of SQL used to define the database's schema and structure.

DML, on the other hand, is concerned with manipulating the data within the database, allowing operations such as inserting, updating, and deleting data records. PL/SQL is a procedural language extension for SQL, mainly used in Oracle databases, which combines SQL with procedural programming constructs but does not focus exclusively on defining database structures.

Understanding these distinctions is vital for navigating database management effectively and recognizing that while SQL encompasses a broader range of functionalities, DDL specifically targets the structural definition aspect.