Dynamic RLS with USERNAME in Power BI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is Dynamic Row-Level Security (RLS) in Power BI?

Dynamic RLS restricts data access based on the logged-in user's identity, allowing different users to see only the data they are permitted to view without creating separate roles for each user.

beginner

What DAX function is commonly used to get the current user's username in Dynamic RLS?

The USERNAME() function returns the domain and username of the logged-in user, which can be used to filter data dynamically.

intermediate

How do you typically set up a Dynamic RLS rule using USERNAME() in Power BI?

You create a role with a DAX filter like [UserEmail] = USERPRINCIPALNAME() or LOWER([UserEmail]) = LOWER(USERPRINCIPALNAME()), matching the logged-in user's email to a column in your data that stores user emails.

intermediate

Why might you use LOWER() with USERPRINCIPALNAME() in Dynamic RLS?

Using LOWER() ensures case-insensitive matching between the logged-in user's email and the email stored in your data, preventing mismatches due to letter case differences.

beginner

What is a common real-life example of Dynamic RLS with USERNAME()?

A sales manager logs in and sees only their region's sales data because the RLS filters data where the sales region matches the manager's username or email, ensuring data privacy and relevance.

Which DAX function returns the current logged-in user's domain and username?

A USEREMAIL()

B USERNAME()

C CURRENTUSER()

D USERID()

USERNAME() returns the domain and username of the logged-in user in Power BI.

In Dynamic RLS, what does the expression [UserEmail] = USERNAME() do?

A Filters data to show only rows where UserEmail matches the logged-in user

B Shows all data regardless of user

C Filters data by date

D Creates a new user account

This expression filters data so users see only rows where the UserEmail matches their username.

Why might you prefer USERPRINCIPALNAME() over USERNAME() in Dynamic RLS?

A USERPRINCIPALNAME() returns the user's phone number

B USERPRINCIPALNAME() returns the user's password

C USERPRINCIPALNAME() is faster to compute

D USERPRINCIPALNAME() returns the user's email address, which is often easier to match

USERPRINCIPALNAME() typically returns the user's email, which is easier to match with email columns in data.

What is the purpose of using LOWER() in a Dynamic RLS filter like LOWER([UserEmail]) = LOWER(USERPRINCIPALNAME())?

A To make the comparison case-insensitive

B To encrypt the email addresses

C To convert emails to uppercase

D To remove spaces from emails

LOWER() converts text to lowercase to ensure case-insensitive matching.

What happens if you do not set up Dynamic RLS correctly in Power BI?

A Power BI will crash

B The report will not load

C Users may see data they should not access

D The report will only show blank pages

Incorrect RLS setup can expose sensitive data to unauthorized users.

Explain how Dynamic RLS works in Power BI using the USERNAME() function.

Think about how Power BI knows who is viewing the report and how it shows only their data.

Describe a step-by-step process to implement Dynamic RLS with USERPRINCIPALNAME() in a Power BI report.

Consider the data setup, role creation, DAX formula, and testing.

Practice

1. What is the main purpose of using USERNAME() in Dynamic Row-Level Security (RLS) in Power BI?

easy

A. To change the report theme dynamically

B. To filter data based on the logged-in user's identity

C. To calculate the total sales amount

D. To create new columns in the data model

Solution

1. Step 1: Understand USERNAME() function

   The USERNAME() function returns the current logged-in user's email or username.

2. Step 2: Apply USERNAME() in Dynamic RLS

   Dynamic RLS uses USERNAME() to filter data so each user sees only their allowed rows.

3. Final Answer:

   To filter data based on the logged-in user's identity -> Option B

4. Quick Check:

   USERNAME() filters data by user [OK]

Hint: USERNAME() filters data by current user identity [OK]

Common Mistakes:

• Thinking USERNAME() creates new columns
• Using USERNAME() to calculate totals
• Confusing USERNAME() with theme settings

2. Which of the following is the correct syntax to create a filter rule for Dynamic RLS using USERNAME() in Power BI?

easy

A. [UserEmail] = USERNAME()

B. FILTER([UserEmail], USERNAME())

C. USERNAME() = [UserEmail]

D. CALCULATE(USERNAME(), [UserEmail])

Solution

1. Step 1: Understand filter rule syntax

   In Dynamic RLS, the filter rule compares a column to the current user using =.

2. Step 2: Identify correct syntax

   The correct syntax is [UserEmail] = USERNAME() to filter rows matching the logged-in user.

3. Final Answer:

   [UserEmail] = USERNAME() -> Option A

4. Quick Check:

   Filter rule uses column = USERNAME() [OK]

Hint: Use column = USERNAME() for filter rules [OK]

Common Mistakes:

• Using USERNAME() on left side of comparison
• Using FILTER() function incorrectly
• Trying to CALCULATE USERNAME()

3. Given a table with a column UserEmail and a Dynamic RLS filter rule [UserEmail] = USERNAME(), what data will a user with email [e-mail] see?

medium

A. Only rows where UserEmail is not [e-mail]

B. All rows regardless of UserEmail

C. Only rows where UserEmail is [e-mail]

D. No rows at all

Solution

1. Step 1: Understand the filter rule effect

   The rule [UserEmail] = USERNAME() filters rows to only those matching the logged-in user's email.

2. Step 2: Apply to user email

   For user [e-mail], only rows with UserEmail = [e-mail] are visible.

3. Final Answer:

   Only rows where UserEmail is [e-mail] -> Option C

4. Quick Check:

   Filter shows rows matching USERNAME() [OK]

Hint: User sees only rows matching their email [OK]

Common Mistakes:

• Assuming user sees all rows
• Thinking user sees rows with different emails
• Believing no rows are shown

4. You wrote this RLS filter rule: FILTER(Users, Users[Email] = USERNAME()). Why does it cause an error in Power BI?

medium

A. FILTER cannot be used directly as a filter rule; it expects a boolean expression

B. USERNAME() is not allowed in RLS rules

C. The column name should be lowercase

D. FILTER requires two arguments

Solution

1. Step 1: Understand RLS filter rule requirements

   RLS filter rules expect a boolean expression, not a table expression like FILTER().

2. Step 2: Identify the error cause

   Using FILTER() returns a table, causing a syntax error in RLS rules.

3. Final Answer:

   FILTER cannot be used directly as a filter rule; it expects a boolean expression -> Option A

4. Quick Check:

   RLS rules need boolean expressions [OK]

Hint: Use boolean expressions, not FILTER(), in RLS rules [OK]

Common Mistakes:

• Using FILTER() instead of boolean condition
• Thinking USERNAME() is disallowed
• Assuming column case matters
• Believing FILTER needs two arguments

5. You want to create Dynamic RLS so that managers see data for their team members, and team members see only their own data. The table has columns UserEmail and ManagerEmail. Which DAX filter rule correctly implements this?

hard

A. USERNAME() = [UserEmail] && USERNAME() = [ManagerEmail]

B. [UserEmail] = USERNAME() && [ManagerEmail] = USERNAME()

C. FILTER(Users, [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME())

D. [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME()

Solution

1. Step 1: Understand the requirement

   Managers should see rows where they are the manager, and users see their own rows.

2. Step 2: Choose correct logical operator

   Use OR (||) to allow either condition: user is the row owner or user is the manager.

3. Step 3: Validate syntax

   [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME() uses correct syntax and logic: [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME().

4. Final Answer:

   [UserEmail] = USERNAME() || [ManagerEmail] = USERNAME() -> Option D

5. Quick Check:

   Use OR (||) to combine user and manager filters [OK]

Hint: Use OR (||) to combine user and manager filters [OK]

Common Mistakes:

• Using AND (&&) instead of OR (||)
• Reversing USERNAME() and column order
• Using FILTER() in RLS rule