Why Dynamic RLS with USERNAME in Power BI? - Purpose & Use Cases

The Big Idea

What if one report could magically show only your data, no matter who you are?

The Scenario

Imagine you have a sales report shared with your entire company. You want each salesperson to see only their own sales data. Without automation, you must create separate reports or filters for every single user.

The Problem

Manually setting filters for each user is slow and error-prone. When new employees join or roles change, you must update filters everywhere. This wastes time and risks exposing sensitive data by mistake.

The Solution

Dynamic Row-Level Security (RLS) with USERNAME() automatically filters data based on who is logged in. It uses the user's login to show only their relevant data, so you create one report that adapts for everyone.

Before vs After

✗ Before

Filter sales where Salesperson = 'JohnDoe'
Filter sales where Salesperson = 'JaneSmith'

✓ After

Filter sales where Salesperson = USERNAME()

What It Enables

Dynamic RLS with USERNAME() lets you securely share one report that customizes itself for each user automatically.

Real Life Example

A company dashboard shows each regional manager only their region's sales without needing multiple reports or manual updates.

Key Takeaways

Manual filtering for each user is slow and risky.

Dynamic RLS with USERNAME() automates data filtering based on login.

This saves time and protects sensitive data effortlessly.

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