What is Data Dictionary in DBMS | MetaData | SQL Developer | PLSQL | Most Asked Interview Question

A data dictionary is a collection of data that describes the structure, relationships, and attributes of the data stored in the database.
The data dictionary contains metadata, which is data about data. It includes information about the tables, columns, and relationships in the database, as well as data types, constraints, and other details about the structure of the data. It also includes information about the users and roles in the database, as well as details about database security and access controls.

The data dictionary is used by the DBMS to manage and access the data in the database. It is also used by database administrators and developers to understand the structure and relationships of the data, and to write and optimize SQL queries.
Some examples of information that might be stored in a data dictionary include:

Table and column names
Data types and sizes of columns
Primary and foreign keys
Indexes and constraints
Relationship between tables
User and role information
Security and access controls
Statistical information about the data
Timestamps for when data was created or modified

A data dictionary is also sometimes referred to as a system catalog or a data directory.

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Who is responsible for creating a data dictionary?