A schema in SQL Server serves as a logical container for organizing database objects, including tables, views, and stored procedures. Each schema possesses a unique identifier, aptly named the schema ID. This ID serves as a reference point for addressing the schema in various SQL operations, such as granting permissions or filtering query results.

Two primary methods exist for retrieving the schema ID of a specified schema in SQL Server:

Leveraging the SCHEMA_ID() Function

The SCHEMA_ID() function, an integral part of SQL Server's repertoire, takes a schema name as input and promptly returns its corresponding schema ID. The syntax for employing the SCHEMA_ID() function is straightforward:

SCHEMA_ID ( [ schema_name ] )

Where schema_name represents the schema whose ID you seek. If no schema name is provided, the function defaults to returning the schema ID of the current user's default schema.

Example:

SELECT SCHEMA_ID('dbo');

This query effectively extracts the schema ID associated with the 'dbo' schema.

Utilizing the sys.schemas System View

The sys.schemas system view encompasses a column named schema_id, which stores the schema ID for each schema within the database. By employing a SELECT statement to interrogate this view, you can readily obtain the schema ID of a specific schema. The syntax for querying sys.schemas is as follows:

SELECT schema_id
FROM sys.schemas
WHERE name = 'schema_name';

Where name represents the schema whose ID you desire.

Example:

SELECT schema_id
FROM sys.schemas
WHERE schema_name = 'dbo';

This query fetches the schema ID associated with the 'dbo' schema.

Both the SCHEMA_ID() function and the sys.schemas system view equip you with the capability to retrieve the schema ID of a given schema. The choice between these methods hinges on your specific requirements. For infrequent schema ID retrieval, the SCHEMA_ID() function offers a straightforward and concise approach. However, for frequent retrieval across multiple schemas, querying sys.schemas may prove more efficient.