Data Dictionary in DBMS
Data Dictionary consists of database metadata. It has records about objects in the database.
What Data Dictionary consists of
Data Dictionary consists of the following information −
- Name of the tables in the database
- Constraints of a table i.e. keys, relationships, etc.
- Columns of the tables that related to each other
- Owner of the table
- Last accessed information of the object
- Last updated information of the object
An example of Data Dictionary can be personal details of a student −
Example
<StudentPersonalDetails>
Student_ID
| Student_Name
| Student_Address
| Student_City
|
The following is the data dictionary for the above fields −
Types of Data Dictionary
Here are the two types of data dictionary −
Active Data Dictionary
The DBMS software manages the active data dictionary automatically. The modification is an automatic task and most RDBMS has active data dictionary. It is also known as integrated data dictionary.
Passive Data Dictionary
Managed by the users and is modified manually when the database structure change. Also known as non-integrated data dictionary.
Published on 03-Jul-2018 17:05:01
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