40 questions with answers for candidates with Freshers — 25 easy, 14 medium, 1 hard.
What interviewers expect: freshers
Freshers are asked about Power BI components, reports versus dashboards, Import versus DirectQuery, Power Query basics, star schema and simple DAX such as SUM, CALCULATE and DIVIDE. Expect a practical task to build a small dashboard from Excel data, and detailed questions about your portfolio projects, including why you chose specific visuals and measures.
This set is weighted towards Power Query and Data Transformation (9), Visualisation and Report Design (6), Data Modelling (6), Power BI Fundamentals (5).
Power Query cleaning Basic DAX measures Star schema basics Portfolio dashboards
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Sales YTD = TOTALYTD([Total Sales], 'Date'[Date], "31/3")
Sales PY = CALCULATE([Total Sales], SAMEPERIODLASTYEAR('Date'[Date]))
YoY % =
VAR cur = [Total Sales]
VAR py = [Sales PY]
RETURN DIVIDE(cur - py, py)
The "31/3" argument makes YTD follow an April to March fiscal year.
02
Why should you set data types correctly in Power Query?
Correct data types make sorting, filtering, aggregation and relationships work properly; text-typed numbers cannot be summed and mismatched key types break relationships. Types also affect compression and model size, for example whole numbers compress better than decimals or text. Set types once near the end of a query and avoid repeated automatic Changed Type steps, which can fail when column names change.
03
What are subscriptions and data alerts in the Power BI Service?
Subscriptions email a snapshot of a report page or dashboard to users on a schedule, or after data refresh, with a link to the live content. Data alerts notify users when a value on a dashboard card, KPI or gauge tile crosses a threshold, such as daily sales below a target. Paginated reports support subscriptions with attachments like PDF or Excel. Power Automate can extend alerts into workflows.
VAR defines a named value inside an expression and RETURN gives the final result. Variables make measures easier to read, avoid repeating the same calculation, which improves performance, and help debugging because you can return an intermediate variable. A variable is evaluated once in the context where it is defined, so its value does not change if later CALCULATE filters are applied.
05
How do you run a DAX query in DAX Studio to test a measure?
EVALUATE
SUMMARIZECOLUMNS(
'Date'[Fiscal Year],
'Product'[Category],
"Sales", [Total Sales],
"Margin", [Margin %]
)
ORDER BY 'Date'[Fiscal Year]
Turn on Server Timings and Clear cache before running to see storage engine and formula engine time. The same EVALUATE syntax works in the DAX query view in Desktop.
06
How do you set up drill-through to a customer details page?
Create a new page named Customer Details, add visuals showing customer information, orders and trends, and drag Customer Name or Customer ID into the Drill through well in the Visualizations pane. Power BI adds a back button automatically. Users can now right-click a customer in any visual and choose Drill through, Customer Details, and the page opens filtered to that customer.
07
How do you stay current with frequent Power BI updates?
Power BI releases features monthly, so I read the monthly update blog and Fabric release notes, try new features on a test report, and follow community experts and forums. I keep a short list of features relevant to our team, such as visual calculations or TMDL view, and share a five-minute demo in team meetings when something will save us effort.
Power Query is the data connection and transformation engine in Power BI, Excel, dataflows and Fabric Data Factory. It lets you connect to hundreds of sources and shape data with a recorded series of steps, such as removing columns, changing types, merging and unpivoting. Behind the interface each step is written in the M language. Steps re-run automatically on every refresh, making cleaning repeatable.
Power BI Free lets a user build in Desktop and use My workspace but not share content. Power BI Pro is needed to publish to shared workspaces and share with other Pro users. Premium Per User adds larger models, more refreshes and premium features per user. Fabric capacity (F SKUs) provides dedicated capacity; at F64 and above, viewers with a free licence can consume shared content.
Create a new page, set Page information, Allow use as tooltip on, and set Canvas settings to the Tooltip size. Add small visuals like a monthly trend line for the hovered item. On the main visual, go to Format, Tooltips, set Type to Report page and select the tooltip page. Fields in the main visual automatically filter the tooltip page on hover.
Product Rank =
IF(
ISINSCOPE('Product'[Product]),
RANKX(ALLSELECTED('Product'[Product]), [Total Sales], , DESC, DENSE)
)
ALLSELECTED ranks within the products visible after slicers, and ISINSCOPE hides the rank on total rows.
12
What is Power BI and what are its main components?
Power BI is a business intelligence platform for connecting to data, modelling it and building interactive reports and dashboards. Main components are Power BI Desktop for building reports, Power BI Service (part of Microsoft Fabric) for publishing, sharing and refresh, Power BI Mobile apps for viewing, the on-premises data gateway for refreshing local sources, and Power BI Report Server for fully on-premises hosting of paginated and Power BI reports.
13
How do you split a full name column and clean text in Power Query?
Select the column, use Transform, Split Column by Delimiter (space, leftmost) to get first and last names. Then use Format, Trim and Clean to remove extra spaces and non-printable characters, and Capitalize Each Word for consistent case. In M:
= Table.TransformColumns(Source, {{"Name", each Text.Proper(Text.Trim(_)), type text}})
14
A slicer on Product Category does not filter the Targets visual. What do you check?
I would check the relationship path in model view: whether Targets is related to the Product or Category dimension at all, whether the relationship is active, and its cross-filter direction. If Targets are at category level, it needs a relationship to a Category table that also filters Product. Also check whether visual interactions were turned off for that slicer and whether the measure uses ALL or REMOVEFILTERS.
15
How do you manage multiple report requests from different departments with tight deadlines?
I log every request with its business goal, deadline and effort, and agree priorities with my manager instead of choosing alone. I reuse shared semantic models so new reports are faster, and I communicate realistic timelines early. In one quarter this helped me deliver eight reports, with two lower-priority ones moved by a week after discussion with requesters, without escalations.
16
Write a measure for sales of a specific category and region.
Electronics North Sales =
CALCULATE(
[Total Sales],
'Product'[Category] = "Electronics",
'Store'[Region] = "North"
)
Multiple filter arguments are combined with AND. Wrap a filter with KEEPFILTERS if it should intersect with an existing slicer selection instead of replacing it.
17
How do you design a KPI card that shows value, target and variance?
Use the new Card visual or a KPI visual with a main measure such as Total Sales, a target measure and a variance percent measure. Add conditional formatting so the variance turns red below target and green above it, and include a small trend if space allows. Keep labels short, such as Sales vs Target, and show the comparison period in the subtitle.
18
Write basic measures for total sales, total cost and profit margin percentage.
Total Sales = SUM(Sales[Amount])
Total Cost = SUMX(Sales, Sales[Qty] * Sales[UnitCost])
Profit = [Total Sales] - [Total Cost]
Margin % = DIVIDE([Profit], [Total Sales])
Format Margin % as a percentage. Building measures on other measures keeps logic in one place and easy to change.
In Desktop use Modeling, View as, select a role and optionally Other user with an email to simulate dynamic RLS, and check visuals show only expected rows. In the Service open the semantic model's Security settings, select a role and use Test as role. Test with real sample users from different regions and a user with no mapping, who should see no data, and confirm totals match expectations.
20
Sales data has region codes, while targets use region names. How do you combine them?
I would create or import a region mapping table with code and name, clean both sides by trimming spaces and fixing case, then merge in Power Query or better, build a Region dimension table with both columns and relate sales by code and targets by name to it. Unmatched rows should be checked using a left anti join so missing mappings are fixed rather than silently dropped.
21
What is a star schema and why is it recommended for Power BI?
A star schema has central fact tables holding numeric events, such as sales lines, linked to dimension tables describing them, such as Date, Product, Customer and Store. Power BI's engine and DAX are optimised for this shape: filters flow cleanly from dimensions to facts, measures are simpler, models compress better and reports run faster. Flat single tables or snowflakes usually need more complex DAX.
22
What is cross-filter direction and why is bi-directional filtering risky?
Cross-filter direction controls which way filters travel across a relationship. Single direction, from the one side to the many side, is the default and safest. Bi-directional lets the fact table filter the dimension too, which can be useful for slicers showing only relevant values, but it can cause ambiguous paths, unexpected results and slower queries. Prefer single direction and use CROSSFILTER inside specific measures when needed.
23
How do you choose the right chart type in Power BI?
Match the chart to the question. Use bar or column charts to compare categories, line charts for trends over time, stacked bars for part-to-whole across few categories, scatter charts for relationships, maps only for true geographic patterns, cards and KPI visuals for single numbers, and tables or matrices when users need exact values. Avoid pie charts with more than four or five slices.
24
What is the difference between Reference and Duplicate in Power Query?
Duplicate copies all the steps of a query into a new independent query, so later changes to the original do not affect it. Reference creates a new query whose source is the output of the original, so it inherits any changes. Reference is useful for building several tables from one staging query, such as dimension tables from a cleaned sales table, while Duplicate is for experimenting separately.
25
What is the difference between a report and a dashboard in Power BI?
A report is a multi-page, fully interactive document built on one semantic model, with slicers, filters, drill-through and cross-highlighting. A dashboard is a single-page canvas in the Power BI Service made of pinned tiles that can come from several reports and models; it is used for a quick at-a-glance view. Dashboards are created only in the Service, while reports are usually built in Desktop.
26
A source table has duplicate customer rows with different spellings of the same name. What do you do?
For exact duplicates, Remove Duplicates on the key column. For spelling variations, use fuzzy matching in Merge Queries with a similarity threshold and transformation table, review results, and maintain a mapping table of approved matches. The best long-term fix is to use a stable customer ID from the source system and report data quality issues to the owner rather than cleaning endlessly in Power BI.
A semantic model, earlier called a dataset, is the published data model behind reports: tables, relationships, measures, hierarchies, security roles and refresh settings. Many reports can connect to one shared semantic model, which keeps business logic and numbers consistent across teams. Certified or promoted endorsements help users find trusted models. Build permission controls who can create new reports on it.
28
Every month a new Excel file arrives in a folder. How do you load all of them automatically?
Use the Folder connector, or SharePoint Folder for files on SharePoint, pointing to the folder, filter to the right file extension and naming pattern, then use Combine Files. Power Query creates a sample-file transform function applied to every file and appends the results. New files dropped into the folder are included on the next refresh, as long as their structure matches the sample.
29
What is a disconnected table and how is it used for what-if analysis?
A disconnected table has no relationship to the model and is used to capture a user's choice through a slicer. For example, a Discount table from 0 to 30 percent created with GENERATESERIES, or the What-if parameter feature, lets a measure read SELECTEDVALUE(Discount[Value]) and calculate projected revenue. Since it does not filter facts, the measure decides how the selection is applied.
Surrogate keys are system-generated integer keys, such as ProductKey, used in dimensions instead of business keys like product codes. They handle changes in business keys, support Type 2 history with multiple rows per business key, and integer keys compress and join better in VertiPaq than long text keys. They are usually created in the data warehouse layer.
Date =
ADDCOLUMNS(
CALENDAR(DATE(2022, 1, 1), DATE(2026, 12, 31)),
"Year", YEAR([Date]),
"Month No", MONTH([Date]),
"Month", FORMAT([Date], "MMM"),
"Quarter", "Q" & QUARTER([Date]),
"Weekday", FORMAT([Date], "ddd")
)
Then mark it as a date table and sort Month by Month No.
32
Your calculated columns have made the model huge. What do you do?
I would move simple row-level logic into Power Query or the source SQL, where it compresses better and can fold, and replace aggregations stored as columns with measures. High-cardinality columns such as concatenated keys or precise timestamps should be removed or split. Then check model size with VertiPaq Analyzer in DAX Studio to confirm which columns used the most memory.
33
What is a decomposition tree and when is it useful?
The decomposition tree is an AI visual that lets users break down a measure across several dimensions in any order, for example splitting a sales drop by region, then category, then channel. It can also suggest the next split automatically using high value or low value analysis. It is useful for root-cause exploration by business users, though it is less suited to fixed reporting.
Key table functions include FILTER, ALL, VALUES, DISTINCT, SUMMARIZE and SUMMARIZECOLUMNS for grouping, ADDCOLUMNS to add calculated columns, TOPN for top rows, CROSSJOIN, UNION, EXCEPT, INTERSECT, GENERATESERIES and TREATAS for virtual relationships. They return tables used inside iterators, CALCULATE filters or calculated tables. ADDCOLUMNS over SUMMARIZE is a common pattern for reliable grouped results.
35
What is the difference between Power Query M and DAX?
M is the language of Power Query, used at refresh time to extract, clean and shape data before it enters the model, such as merging tables or splitting columns. DAX is used after data is loaded, to define measures, calculated columns and security that evaluate in filter context at query time. As a rule, do row-level shaping in M or the source and dynamic calculations in DAX.
36
What is conditional formatting and where can you apply it?
Conditional formatting changes colours, icons, data bars or font based on values or rules, helping users spot good and bad performance quickly. You can apply it to table and matrix cells, backgrounds, font colour, chart data colours and titles using field values, rules or a measure that returns a colour code. A measure returning hex colours gives full control, such as red when below target.
37
How do you add a conditional column in Power Query?
Use Add Column, Conditional Column and define rules, or write M directly:
= Table.AddColumn(Source, "Band", each
if [Amount] >= 100000 then "High"
else if [Amount] >= 25000 then "Medium"
else "Low", type text)
Adding the type at the end avoids an extra Changed Type step. Conditional columns built here are computed at refresh, not at query time.
38
A business user asks to merge customer and sales into one table to make it easier. How do you respond?
I would explain that a star schema with separate Customer and Sales tables is easier for them in practice: slicers are cleaner, totals are correct and reports run faster. To keep it user-friendly I would hide key columns, organise measures in display folders and name fields in plain language. I would show them the field list so they see simplicity on the surface.
39
How do you connect Power BI Desktop to a SQL Server database?
Use Home, Get Data, SQL Server. Enter the server name and optionally the database, choose Import or DirectQuery, and optionally paste a native SQL query under Advanced options. Choose Windows or database authentication, then pick tables in the Navigator and select Transform Data to clean them in Power Query. For scheduled refresh of an on-premises server, an on-premises data gateway must be configured in the Service.
40
What modelling practices reduce Power BI model size?
Remove unused columns and rows, avoid high-cardinality columns like GUIDs and datetime with seconds by splitting date and time or rounding, use integer surrogate keys, prefer measures over calculated columns, turn off Auto date/time, and choose the right data types, such as fixed decimal. Load only the history users need, and summarise data where detail is not required.
Frequently asked questions
What is asked in Power BI interviews for Freshers?
Freshers are asked about Power BI components, reports versus dashboards, Import versus DirectQuery, Power Query basics, star schema and simple DAX such as SUM, CALCULATE and DIVIDE. Expect a practical task to build a small dashboard from Excel data, and detailed questions about your portfolio projects, including why you chose specific visuals and measures.
How many questions should I practise before a Power BI interview?
Work through all 40 questions here, then the company-wise sets for the employers you are targeting. Quality matters more than count: be able to explain why each answer is right.
Which topics matter most for Freshers?
Focus first on Power Query cleaning, Basic DAX measures, Star schema basics, Portfolio dashboards.