Database Languages

Broadly speaking, there are two categories of database languages:

Data Manipulation Language (DML)

It is also known as query language
It is used to access and manipulate the data stored in a database
It has two sub-categories: procedural (the user specifies what data is required and how to compute the data) and declarative/non-procedural (the user specifies what data is required without specifying how to compute the data)
SQL (Structured Query Language) is the most widely used query language and is non-procedural
Some common DML commands include SELECT, INSERT, UPDATE, DELETE

It is used to define the database schema, the storage structure, integrity constraints and the authorizations on the database content and operations
The DDL compiler generates a set of tables stored in a data dictionary
The data dictionary contains metadata including the database schema, the storage structure (specified using data storage and definition language), integrity constraints (such as domain constraints, referential integrity, assertions etc) and authorization information
Some common DDL commands include CREATE, ALTER, DROP

SQL is, therefore, both a DML and a DDL.

Last updated 4 years ago