What is the role of the information_schema database in a relational database management system? Print

The information_schema database is an ANSI/ISO-standard schema in relational database management systems (RDBMS) that provides a comprehensive view of the metadata associated with each database. It acts as a catalog that houses metadata about tables, views, stored procedures, columns, constraints, and other database objects.

Key Features of information_schema

1. Metadata Storage: It stores metadata about all the objects in the database, such as tables, columns, views, and procedures.
2. Read-Only Views: The information_schema consists of read-only views that provide information about the database objects.
3. Standardization: It offers a consistent way to access and retrieve valuable information about the database structure across different RDBMSs like MySQL, PostgreSQL, MariaDB, and SQL Server.

Common information_schema Tables

Here are some of the commonly used tables in the information_schema:

• TABLES: Provides information about tables in the databases.
• COLUMNS: Provides information about columns in the tables.
• ROUTINES: Provides information about stored routines (stored procedures and functions).
• VIEWS: Provides information about views in the databases.
• CHECK_CONSTRAINTS: Provides information about CHECK constraints.

Example Queries

Below are some example queries to retrieve information from the information_schema:

List All Tables in a Database

SELECT table_name
FROM information_schema.tables
WHERE table_schema = 'your_database_name';

List All Columns in a Specific Table

SELECT column_name, data_type, is_nullable
FROM information_schema.columns
WHERE table_name = 'your_table_name';

List All Views in a Database

SELECT table_name
FROM information_schema.views
WHERE table_schema = 'your_database_name';

List All Stored Procedures

SELECT routine_name, routine_type
FROM information_schema.routines
WHERE routine_schema = 'your_database_name';

Benefits of Using information_schema

• Portability: The same queries can be used across different database systems that support the information_schema.
• Consistency: Provides a standardized way to access metadata, making it easier to manage and understand the database structure.
• Security: Since the views are read-only, it ensures that the metadata cannot be altered accidentally.

Conclusion

The information_schema database is an essential tool for database administrators and developers, providing a standardized and comprehensive way to access metadata about the database objects. By using the information_schema, you can efficiently manage and retrieve information about your database structure.