PL-300 Prepare the data Practice Question
You are a Power BI data analyst at a university. You import a table named Enrollments from an on-premises SQL Server database. The table contains a column named StudentEmail that is stored as text and sometimes has leading or trailing spaces. You need to remove these spaces so that the column can be used to create a relationship with a Students table that also has a StudentEmail column. You must perform this cleanup in Power Query, and the transformation must apply to the entire column without creating a new column. Which transformation should you use?
⚠ Common exam trap
The trap here is selecting Trim from the Add Column tab instead of the Transform tab, which creates a new column and leaves the original column with the unwanted spaces.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
On the Transform tab, select Format and then Trim.
Trim is the Power Query transformation that removes leading and trailing whitespace from text values in place. Applying it from the Transform tab modifies the existing StudentEmail column, so the cleaned values can match the Students table and support the relationship. The Add Column variant would create a separate column, and Clean or Replace Values do not correctly remove only the surrounding spaces.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
On the Transform tab, select Format and then Trim.
Why this is correct
The Trim transformation removes leading and trailing whitespace from text values across the entire selected column. It modifies the existing column in place, which matches the requirement to avoid creating a new column. After trimming, the values can match the Students table and support a valid relationship. This is the standard data cleansing step for text keys.
- ✗
On the Add Column tab, select Format and then Trim.
Why it's wrong here
Using Trim from the Add Column tab creates a new column containing the trimmed values while leaving the original column unchanged. The scenario explicitly requires the transformation to apply to the entire column without creating a new column. Although the new column would have correct values, the original StudentEmail column would remain untrimmed and the relationship would still fail.
- ✗
On the Transform tab, select Replace Values and replace a space with an empty value.
Why it's wrong here
Replace Values replaces every occurrence of the specified substring, including spaces inside email addresses or names, which would corrupt the data. It also does not selectively target leading and trailing spaces. This approach would damage valid values and is not a safe way to trim whitespace from a column used as a relationship key.
- ✗
On the Transform tab, select Format and then Clean.
Why it's wrong here
The Clean transformation removes non-printable characters, such as control codes, but it does not remove ordinary leading and trailing spaces. Spaces are printable characters, so the values would remain with their extra whitespace and the relationship would still not match. Clean is not the correct tool for stripping spaces from text keys.
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Last reviewed September 2026 · checked against the official Microsoft exam blueprint
This PL-300 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PL-300 exam.