The document discusses data dictionaries, which contain metadata about the data in a database. It notes that there are two types: active dictionaries that automatically update with the database, and passive dictionaries that are separate and not automatically updated. The document also lists some key advantages of data dictionaries like providing organized data lists and maintaining integrity across databases. Finally, it briefly introduces the three main types of data: structured, unstructured, and semi-structured.

1. Data Dictionary
By Lakshya

2. Data Dictionary
• Data Dictionary contains metadata about the data.
• For Example:- The index of the book is meta data
• Data dictionary contain the information about database
like what is in the database access and storage
information.
• It is handled by database administrators.

3. Types of Data
Dictionary
There are two types of data dictionaries: Active and Passive
• Active data dictionaries are created within the databases they describe and automatically reflect any
updates or changes in their host databases. This avoids any discrepancies between the data
dictionaries and their database structures.
• Passive data dictionaries are created separately from the database which are not updated
automatically.

4. Operations of
Data Dictionary
1. Create
2. Updation/Insertion
3. Deletion
4. User administration

5. Advantage of Data Dictionary
• Provides organized, comprehensive lists of data
• Easily searchable
• Provides reporting and documentation for data across multiple programs
• Simplifies the structure for system data requirements
• Reduces data redundancy
• Maintains data integrity across multiple databases; and
• Provides relationship information between different database tables

6. Disadvantage of Data Dictionary
• Lack of functional details regarding data
• Diagrams that are not always visually appealing
• Can be difficult for nontechnical users to understand.

7. Data and It's Types
Data are observations or measurements (unprocessed or processed) represented as text,
numbers, or multimedia.
Data are generally categories in 3 types
1.Structured Data -Organized and formatted data.Examples include data in relational
databases with defined tables and fields.
2.Unstructured Data-Lacks a predefined data model or structure.Examples include text
documents, images, and videos,Information Retrieval.
3.Semi-Structured Data-Has some level of structure but doesn't fit neatly into a relational
database.Examples include DW,No SQL