Append vs Merge in Power Query: Which to Use?
Which TWO of the following are valid methods to combine data from multiple sources in Power BI?
Quick Answer
The correct answer is that both Append Queries and Merge Queries are valid methods to combine data from multiple sources in Power BI, but they serve fundamentally different purposes. Append Queries stacks rows from two or more tables into a single table, functioning like a SQL UNION operation—ideal when you have identical column structures across sources, such as combining monthly sales files. Merge Queries, on the other hand, joins columns based on matching keys, similar to SQL JOINs, and is used to enrich or relate tables. On the PL-300 exam, this distinction tests your ability to choose the right transformation for the data shape required; a common trap is confusing Append for column-based consolidation or Merge for row-based stacking. Remember the memory tip: Append adds rows (think “add rows”), Merge adds columns (think “merge columns”).
⚠ Common exam trap
Many exam-takers confuse data transformation operations (like Pivot, Unpivot, Group By) with data combination operations (Append and Merge), leading them to select options that modify existing data rather than integrate multiple sources.
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
✓
Append Queries
Append Queries is a valid method to combine data from multiple sources in Power BI because it stacks rows from two or more tables into a single table, which is essential when you have similar data structures across different sources (e.g., monthly sales files). This operation is performed in Power Query Editor and corresponds to a UNION operation in SQL, making it a standard data preparation technique.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Pivot Column
Why it's wrong here
Transforms data from rows to columns.
- ✓
Append Queries
Why this is correct
Appends rows from one query to another.
- ✗
Unpivot Columns
Why it's wrong here
Transforms data from columns to rows.
- ✓
Merge Queries
Why this is correct
Merges columns based on a matching key.
- ✗
Group By
Why it's wrong here
Aggregates data, does not combine sources.
Go deeper
Related to this question
About these practice questions
Courseiva writes every PL-300 question from scratch — 217 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
4 more ways this is tested on PL-300
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which TWO are valid ways to combine data from multiple sources in Power Query? (Choose two.)
easy- A.Pivot Column.
- ✓ B.Append Queries.
- C.Create relationships in the data model.
- ✓ D.Merge Queries.
- E.Group By.
Why B: The Append Queries operation in Power Query combines rows from two or more tables by stacking them vertically, which is a standard way to consolidate data from multiple sources when the columns are aligned. This is distinct from merging, which combines columns based on matching keys.
Variation 2. You need to combine data from two tables in Power Query that have the same columns but different row sets. Which operation should you use?
easy- A.Union Queries
- B.Group By
- ✓ C.Append Queries
- D.Merge Queries
Why C: Append Queries is the correct operation in Power Query when you need to combine two tables with identical columns but different row sets. It stacks the rows from the second table beneath the rows from the first table, effectively performing a union of the data. This is distinct from Merge Queries, which joins columns based on a key, and Group By, which aggregates data.
Variation 3. Which TWO options are valid methods to combine multiple tables in Power Query?
medium- A.Join
- B.Concatenate
- ✓ C.Merge
- D.Union
- ✓ E.Append
Why C: (Merge) is correct because Merge in Power Query performs a join-like operation that combines columns from two tables based on a matching key, similar to SQL JOINs. Option E (Append) is correct because Append stacks rows from multiple tables with the same columns, akin to SQL UNION ALL. Both are native Power Query operations for combining tables.
Variation 4. You have a Power BI dataset that combines sales data from two Excel files: Sales2023.xlsx and Sales2024.xlsx. Both files have the same schema. You need to combine them into a single table without duplicating rows. What is the best approach in Power Query?
medium- A.Use Union in DAX.
- B.Use Group By to summarize data.
- ✓ C.Use Append Queries.
- D.Use Merge Queries as a new query.
Why C: Append Queries in Power Query is specifically designed to combine rows from two or more tables with the same schema into a single table, stacking them vertically without duplicating rows. This operation is performed in the Power Query Editor (M language) and is the standard approach for unioning data from multiple sources during the data preparation phase, before loading into the Power BI data model.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.