A database system provides several types of languages to interact with the database. These include:
Data Definition Language (DDL): DDL is used to define the structure of the database, including tables, relationships, and constraints. DDL statements create, modify, and delete database objects. Examples of DDL statements include CREATE, ALTER, and DROP.
Data Manipulation Language (DML): DML is used to manipulate the data stored in the database. DML statements include SELECT, INSERT, UPDATE, and DELETE. These statements allow users to add, update, and delete data from the database, and to retrieve data in various forms.
Data Control Language (DCL): DCL is used to control access to the database. DCL statements include GRANT and REVOKE, which are used to grant or revoke privileges to users, roles, or groups. DCL also includes commands to manage transactions and control locking behavior.
Transaction Control Language (TCL): TCL is used to manage transactions in the database. TCL statements include COMMIT and ROLLBACK, which are used to commit or roll back transactions. TCL is used to ensure data consistency and integrity.
Procedural Language: Some database systems provide a procedural language for creating stored procedures, functions, and triggers. These are used to automate common tasks and to enforce business rules. Examples of procedural languages include PL/SQL for Oracle, T-SQL for SQL Server, and PL/pgSQL for PostgreSQL.
Query Language: Query languages are used to retrieve data from the database. SQL (Structured Query Language) is the most commonly used query language for relational databases. Other query languages include XQuery for XML databases and SPARQL for semantic web databases.
These languages provide different ways of interacting with a database system, allowing users to define, manipulate, control, and query data in various ways.
