Answer: a database scoped credential

## Explanation When querying Azure Blob Storage from Azure Synapse Analytics serverless SQL pool using Shared Access Signature (SAS) authorization without defining a data source, the correct approach is to create a **database-scoped credential**. ### Why Database-Scoped Credential (Option D) is Correct: - **SAS Token Storage**: Database-scoped credentials are specifically designed to store authentication information, including SAS tokens, at the database level within Synapse Analytics. - **Ad-hoc Query Support**: This credential type enables ad-hoc queries using functions like `OPENROWSET` without requiring the creation of external data sources or external tables. - **Direct Access**: With a database-scoped credential containing the SAS token, you can directly query storage using syntax like: ```sql SELECT * FROM OPENROWSET( BULK 'https://storage1.blob.core.windows.net/container/file.csv', FORMAT = 'CSV', CREDENTIAL = 'my_scoped_credential' ) AS [result] ``` - **Security Scope**: The credential is scoped to the specific database, providing appropriate security boundaries. ### Why Other Options Are Incorrect: - **Stored Access Policy (Option A)**: This is an Azure Storage feature for managing SAS tokens at the storage account level, not a Synapse Analytics authentication mechanism for querying storage. - **Server-Level Credential (Option B)**: Server-level credentials exist in dedicated SQL pools but are not available or appropriate for serverless SQL pools in Synapse Analytics. - **Managed Identity (Option C)**: While managed identities provide excellent authentication for many Azure services, they are not used for SAS token-based authentication scenarios and would require different configuration approaches. ### Best Practice Consideration: Using database-scoped credentials with SAS tokens provides a secure and flexible method for ad-hoc queries while maintaining the principle of least privilege, as the SAS token can be configured with specific permissions and expiration times.

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