Column operations (rename, remove, reorder) in Power BI - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ dax_lod_result

intermediate

DAX Measure Result After Column Rename

You have a table named Sales with columns ProductID, Quantity, and Price. You rename the column Price to UnitPrice. Which DAX measure will correctly calculate total sales amount after this rename?

A Total Sales = SUMX(Sales, Sales[Quantity] * Sales[UnitPrice])

B Total Sales = SUMX(Sales, Sales[Quantity] * Sales[Price])

C Total Sales = SUM(Sales[Quantity] * Sales[UnitPrice])

D Total Sales = SUMX(Sales, Quantity * UnitPrice)

💡 Hint

Remember that after renaming, the old column name Price no longer exists.

Option A uses the new column name UnitPrice correctly inside SUMX. Option A uses the old name Price which no longer exists and causes an error. Option A tries to multiply columns inside SUM which is invalid. Option A omits the table name prefix, causing an error.

❓ visualization

intermediate

Best Practice for Column Reordering in a Table Visual

You want to display a table visual in Power BI showing Customer Name, Order Date, and Sales Amount. You reorder columns in the data model to Order Date, Customer Name, Sales Amount. What will be the order of columns shown in the table visual?

A Order Date, Customer Name, Sales Amount

B Order Date, Sales Amount, Customer Name

C Sales Amount, Customer Name, Order Date

D Customer Name, Order Date, Sales Amount

💡 Hint

Remember that column order in the data model does not automatically change visual column order.

Power BI visuals display columns in the order you add them to the visual, not the data model column order. So if you add Customer Name first, it appears first regardless of data model order.

❓ data_modeling

advanced

Removing Columns to Optimize Model Size

You have a large dataset with columns OrderID, CustomerID, OrderDate, TempNotes, and DiscountCode. You want to reduce model size by removing unnecessary columns. Which column should you remove if TempNotes is only used for temporary comments during data import and never in reports?

A Remove <code>TempNotes</code> column

B Remove <code>OrderID</code> column

C Remove <code>CustomerID</code> column

D Remove <code>OrderDate</code> column

💡 Hint

Think about which columns are essential for analysis and which are not.

TempNotes is only for temporary use and not needed in reports, so removing it reduces model size without losing report functionality. Other columns are likely important for analysis.

🎯 Scenario

advanced

Reordering Columns for User-Friendly Data Entry

You are designing a Power BI data entry form using Power Apps integration. The source table has columns FirstName, LastName, Email, Phone. Users want the form to show LastName first, then FirstName, then Email, and finally Phone. How do you ensure this column order in the form?

A Rename columns to include numbers to force order

B Reorder columns in the Power Apps form layout manually

C Reorder columns in the data model to the desired order

D Remove columns and add them back in desired order

💡 Hint

Think about where the form layout is controlled.

The form layout in Power Apps is controlled inside the app, so you reorder fields there manually. Changing data model column order does not affect form layout.

🔧 Formula Fix

expert

Debugging Column Rename Impact on Existing Reports

You renamed a column SalesAmount to TotalSales in your data model. After refreshing, some reports show errors. Which of the following is the most likely cause?

A The column <code>TotalSales</code> was removed instead of renamed

B The data type of <code>TotalSales</code> changed automatically causing errors

C Existing visuals and measures still reference the old column name <code>SalesAmount</code>

D The data model refresh failed due to network issues

💡 Hint

Think about what happens when you rename a column but do not update dependent objects.

Renaming a column breaks references in visuals and measures that still use the old name SalesAmount. This causes errors until those references are updated to TotalSales.