Managing user authentication and authorization is one of the key responsibilities of a database administrator. When working with Microsoft Azure SQL Database, one of the main ways to accomplish this task is by using Transact-SQL (T-SQL).

Authentication refers to the process of verifying user identities, making sure the people trying to access your systems are who they claim to be. Authorization, on the other hand, deals with permissions — once a user’s identity is verified, what are they allowed to do within the DB?

With SQL Server, the DBA has several options for managing these aspects of security, including integrated security (Windows authentication), SQL Server authentication, and Azure Active Directory – Universal with MFA authentication. In Azure SQL Database and Azure SQL Data Warehouse, however, only two types of authentication are supported: SQL Server authentication and Azure Active Directory (AD) authentication.

Using T-SQL, you can manage these aspects of security easily.

Table of Contents

Creating Logins and Users

Authentication in SQL Server is carried out at the server level. You authenticate to the server by using a login. This login can be a Windows login or a SQL Server login. When dealing with Azure SQL servers, only SQL logins are applicable.

Here’s how you can create a new SQL Server login using T-SQL:

CREATE LOGIN [LoginName]
WITH PASSWORD = ‘password’;

Once the login is created, you can then create a database user and associate it with this login. Authorization in SQL Server is carried out at the database level, and this is where users come in.

USE [DatabaseName]
CREATE USER [UserName]
FOR LOGIN [LoginName];

With these commands, we have created a new user, associated with the login that we previously created at the server level.

Assigning Roles and Permissions

Once users are created, you can manage their permissions by granting or denying them certain roles. Roles are a collection of permissions. For instance, the `db_datareader` role allows a user to read all data from all tables in a database.

Here’s how you can add a user to a role:

EXEC sp_addrolemember ‘db_datareader’, ‘UserName’;

You can remove a user from a role using `EXEC sp_droprolemember`, and you can check which roles a user is a part of using `EXEC sp_helprolemember`.

You can also grant, deny, or revoke individual permissions to users. The following example grants the SELECT permission on the Person.Address table to a user:

GRANT SELECT ON OBJECT::Person.Address TO UserName;

Managing Azure Active Directory Authentication

Azure Active Directory (AD) authentication is a more modern method of authentication, supported by both Azure SQL Database and SQL Data Warehouse.

Azure AD authentication uses identities managed by Azure Active Directory and provides superior security and seamless integration with other Azure AD-protected services.

Here’s an example of how you can add an Azure AD account as a database user:

CREATE USER [UserName]
FROM EXTERNAL PROVIDER;

Managing authentication and authorization in SQL Server and Azure SQL Database/SQL Data Warehouse is of paramount importance to maintain the security of your data. By understanding these T-SQL commands and practices, you can ensure that only authorized users have access to the appropriate data and database functionality. In addition to these T-SQL commands, DBAs may also use Azure portal, SSMS, or PowerShell for managing authentication and authorization.

It’s always crucial to follow the principle of least privilege — only grant the minimum permissions required for users to perform their tasks. This reduces potential damage in case of any security breach. Keep checking the official documentation as Microsoft continues to improve and update their security practices.

In conclusion, managing authentication and authorization by using T-SQL is a critical skill for taking the DP-300 Exam and for day-to-day administration of SQL solutions on Azure.

Please note that use examples are for educational purposes, it’s important to use strong, secure passwords, and avoid storing them in plain text or in any easily accessible manner.

Practice Test

True/False: T-SQL stands for Transact-Structured Query Language.

  • True
  • False

Answer: True

Explanation: Transact-SQL (T-SQL) is Microsoft’s and Sybase’s proprietary extension to the SQL (Structured Query Language) used to interact with relational databases.

Which of the following statements can be used to grant a permission in SQL Server?

  • A) EXECUTE
  • B) CREATE
  • C) GRANT
  • D) ALTER

Answer: C) GRANT

Explanation: The GRANT statement is used to grant permissions to a user or role.

Multiple select: Which of the following are valid T-SQL statements for managing authentication and authorization?

  • A) GRANT
  • B) DENY
  • C) REPEAL
  • D) REVOKE

Answer: A) GRANT, B) DENY, and D) REVOKE

Explanation: GRANT, DENY, REVOKE are T-SQL commands for managing permissions or authorizations.

True/False: The DENY statement is used to grant permission on a securable in SQL Server.

  • True
  • False

Answer: False

Explanation: The DENY statement is used to deny permissions, not grant them.

Which of the following T-SQL command should be used to remove permissions?

  • A) GRANT
  • B) DENY
  • C) REVOKE
  • D) REMOVE

Answer: C) REVOKE

Explanation: The REVOKE statement is used to remove existing permissions granted or denied.

True/False: The GRANT statement can only be used to provide permissions, not to take them away.

  • True
  • False

Answer: True

Explanation: The GRANT statement is used to grant permissions. To remove permissions, the REVOKE statement is used.

In SQL Server, ‘Securables’ refer to which of the following?

  • A) A list of permissions
  • B) Server resources that can be secured
  • C) Server resources that cannot be accessed
  • D) Users without any permissions

Answer: B) Server resources that can be secured

Explanation: In SQL Server, ‘Securables’ refer to the server resources that can be secured by assigning permissions.

Multiple select: Which types of authentication does SQL Server support?

  • A) Windows Authentication
  • B) SQL Server Authentication
  • C) Azure Active Directory Authentication
  • D) Microsoft Authentication

Answer: A) Windows Authentication, B) SQL Server Authentication, C) Azure Active Directory Authentication

Explanation: SQL Server supports three types of authentication: Windows Authentication, SQL Server Authentication, and Azure Active Directory Authentication.

True/False: CREATE USER statement is used to create a new database user.

  • True
  • False

Answer: True

Explanation: In SQL Server, the CREATE USER statement is used to create a database user to manage the login and access to the database.

Which of the following T-SQL command should be used to create a role in SQL Server?

  • A) CREATE ROLE
  • B) CREATE USER
  • C) CREATE PROFILE
  • D) CREATE GROUP

Answer: A) CREATE ROLE

Explanation: The CREATE ROLE statement is used to create a new role in SQL Server.

True/False: You can use the DENY statement to prevent specific users from accessing specific objects.

  • True
  • False

Answer: True

Explanation: The DENY statement is used in SQL Server to deny specific permissions to a principal for a securable.

Multiple select: What functionality does the SQL Server provide you with to manage authentication and authorization?

  • A) Create users
  • B) Assign roles
  • C) Log user activity
  • D) Grant permissions

Answer: A) Create users, B) Assign roles, D) Grant permissions

Explanation: SQL Server provides you with functionality to create users, assign roles and grant permissions. It does not natively log user activity.

True/False: SQL Server uses role-based authorization to simplify the management of securables.

  • True
  • False

Answer: True

Explanation: Role-based authorization can be used to assign the same set of permissions to a group of users.

Which SQL Server exist at the server level and have permissions that apply to the entire server?

  • A) Server-wide Principals
  • B) Server-wide Security
  • C) Server-wide Role
  • D) Server-wide Legitimation

Answer: A) Server-wide Principals

Explanation: Server-wide principals in SQL Server are security entities that exist at the server level, not just the database level.

True/False: Authorization determines what data a user can access, but authentication determines whether a user has the correct permissions to perform an action.

  • True
  • False

Answer: False

Explanation: Authentication is the process of proving the identity of a user, while Authorization determines what data a user can access and what actions they can perform.

Interview Questions

Q1: How do you create a login account in SQL Server using ‘T-SQL’?

A1: You can create a login account using the CREATE LOGIN command. For example “CREATE LOGIN MyLogin WITH PASSWORD = ‘MyPassword’”.

Q2: What would you use to provide a user with permission to select data from a particular table in SQL Server using ‘T-SQL’?

A2: You would use the GRANT command. For example “GRANT SELECT ON MyTable TO MyUser”.

Q3: How can you revoke a previously granted permission using ‘T-SQL’?

A3: You can use the REVOKE command. For example “REVOKE SELECT ON MyTable FROM MyUser”.

Q4: Which T-SQL command would you use to create a user in the database?

A4: The CREATE USER command is used to create a user in the database. For example “CREATE USER MyUser FOR LOGIN MyLogin”.

Q5: If a user needs to modify data in a SQL Server table, which T-SQL command would you use?

A5: You would use the GRANT command. For example, “GRANT UPDATE ON MyTable TO MyUser”.

Q6: How can you create a role in SQL Server using ‘T-SQL’?

A6: You can create a role using the CREATE ROLE command. For example “CREATE ROLE MyRole”.

Q7: How can you add a user to a SQL Server role using ‘T-SQL’?

A7: You can add a user to a role using the SP_ADDROLEMEMBER system procedure. For example “EXEC SP_ADDROLEMEMBER ‘MyRole’, ‘MyUser’”.

Q8: What ‘T-SQL’ command do you use to drop a user from a database in SQL Server?

A8: You need to use the DROP USER command, such as “DROP USER MyUser”.

Q9: In what situation would you use the DENY command in ‘T-SQL’?

A9: The DENY command is used when you want to restrict a user from performing certain operations on a database object. For example “DENY UPDATE ON MyTable TO MyUser”.

Q10: Can a user be a part of multiple roles in SQL Server? How does it affect permissions?

A10: Yes, a user can be part of multiple roles in SQL Server. The permissions granted to or denied from the user will be the cumulative permissions of all roles they belong to.

Q11: What T-SQL command would you use to alter a login’s password?

A11: You would use the ALTER LOGIN command. For example, “ALTER LOGIN MyLogin WITH PASSWORD = ‘NewPassword’”

Q12: How do you remove a role from a user using T-SQL?

A12: You can use the SP_DROPROLEMEMBER system procedure. For example, “EXEC SP_DROPROLEMEMBER ‘MyRole’, ‘MyUser’”.

Q13: How do you list all users who have access to a particular database using T-SQL?

A13: You can use the SP_HELPROLE procedure. For example “EXEC SP_HELPROLE ‘public’”.

Q14: How do you control access to views using T-SQL?

A14: Access to views can be controlled through the GRANT, REVOKE, and DENY statements. For example “GRANT SELECT ON MyView TO MyUser”.

Q15: How can you change the owner of a schema in SQL Server using ‘T-SQL’?

A15: You can change the owner of a schema using the ALTER AUTHORIZATION command. For example “ALTER AUTHORIZATION ON SCHEMA::MySchema TO MyUser”.

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