Data type changes in Power BI - Step-by-Step Guide

Introduction

Changing data types in Power BI helps make sure your data is understood correctly. This fixes problems like numbers being treated as text or dates not recognized properly. It ensures your reports and calculations work as expected.

When a column with numbers is imported as text and you want to perform calculations.

When date values are not recognized and you need to analyze data over time.

When you want to convert a decimal number to a whole number for counting.

When you need to change a text column to a category for filtering.

When you want to fix errors caused by wrong data types in visuals.

Steps

Step 1: Click

- Data view in Power BI Desktop

The table data is shown with columns and rows

💡 Use Data view to see actual data values and types

Step 2: Select

- Column header of the column you want to change

The column is highlighted and its properties appear in the ribbon

Step 3: Click

- Modeling tab on the ribbon

Modeling options appear including Data Type dropdown

Step 4: Click

- Data Type dropdown in the Modeling tab

A list of data types appears

💡 Common types include Text, Whole Number, Decimal Number, Date/Time

Step 5: Select

- The desired data type from the dropdown

The column data type changes and data is reformatted accordingly

Step 6: Check

- Data view and visuals

Data behaves correctly with the new type in calculations and filters

Before vs After

Before

Column 'Sales' is treated as Text showing values like '1000', '2000', '3000' but cannot be summed

After

Column 'Sales' is changed to Whole Number and can be summed in visuals and calculations

Settings Reference

Data Type

📍 Modeling tab > Data Type dropdown

Defines how Power BI interprets and processes the column data

Default: Based on data import

Common Mistakes

Changing data type without checking data format

Data may not convert properly causing errors or blank values

Preview data first and ensure values match the target type format before changing

Changing data type in report view instead of data or model view

Data type options are not available in report view

Always change data types in Data view or Model view

Summary

Changing data types ensures data is interpreted correctly for analysis.

Use the Modeling tab in Data view to change column data types.

Always check data format before changing to avoid errors.

Practice

1. Why is it important to change data types correctly in Power BI?

easy

A. Because it speeds up the internet connection

B. Because it changes the color of the visuals automatically

C. Because it deletes duplicate rows in the dataset

D. Because it helps Power BI understand and process data accurately

Solution

1. Step 1: Understand the role of data types in Power BI

   Data types tell Power BI how to treat each column, like numbers or text.

2. Step 2: Recognize the impact of correct data types

   Correct types ensure calculations and visuals work properly without errors.

3. Final Answer:

   Because it helps Power BI understand and process data accurately -> Option D

4. Quick Check:

   Correct data types = Accurate processing [OK]

Hint: Data types guide Power BI how to handle data [OK]

Common Mistakes:

• Thinking data types change visual colors
• Believing data types remove duplicates
• Assuming data types affect internet speed

2. Which of the following is the correct way to change a column's data type to Whole Number in Power Query Editor?

easy

A. Right-click the column header, select 'Change Type' > 'Whole Number'

B. Double-click the column header and type 'Whole Number'

C. Click 'Home' tab and press 'Delete' key

D. Drag the column to the 'Values' area

Solution

1. Step 1: Recall how to change data types in Power Query Editor

   Right-clicking the column header opens a menu with 'Change Type' options.

2. Step 2: Identify the correct option for Whole Number

   Selecting 'Whole Number' under 'Change Type' sets the column data type correctly.

3. Final Answer:

   Right-click the column header, select 'Change Type' > 'Whole Number' -> Option A

4. Quick Check:

   Right-click > Change Type > Whole Number [OK]

Hint: Use right-click menu to change data types quickly [OK]

Common Mistakes:

• Trying to type data type directly in header
• Pressing Delete key removes data, not changes type
• Dragging columns changes layout, not data type

3. Given a column 'Sales' with text data type containing values like '100', '200', '300', what will be the result of this DAX measure after changing 'Sales' to Whole Number type?

Total Sales = SUM('Table'[Sales])

medium

A. It will return an error because SUM cannot be used on numbers

B. It will concatenate the text values: '100200300'

C. It will sum the numbers correctly: 600

D. It will return zero because the column is text

Solution

1. Step 1: Understand the effect of changing 'Sales' to Whole Number

   Changing 'Sales' from text to whole number converts values like '100' to 100 as numbers.

2. Step 2: Evaluate the SUM function on numeric data

   SUM adds numeric values, so 100 + 200 + 300 = 600.

3. Final Answer:

   It will sum the numbers correctly: 600 -> Option C

4. Quick Check:

   SUM of numbers = 600 [OK]

Hint: SUM works only on numeric data types [OK]

Common Mistakes:

• Expecting SUM to concatenate text
• Thinking SUM causes error on numbers
• Assuming text columns sum to zero

4. You changed a date column's data type to Text in Power Query, but your visuals show incorrect dates. What is the likely problem?

medium

A. Text data type improves date calculations automatically

B. Changing date to text breaks date calculations and sorting

C. Power BI ignores data types in visuals

D. You must refresh the data source to fix visuals

Solution

1. Step 1: Analyze the impact of changing date to text

   Changing a date column to text removes date properties, so calculations and sorting fail.

2. Step 2: Understand why visuals show incorrect dates

   Without date type, Power BI cannot interpret or order dates properly in visuals.

3. Final Answer:

   Changing date to text breaks date calculations and sorting -> Option B

4. Quick Check:

   Date as text breaks date logic [OK]

Hint: Keep date columns as Date type for correct visuals [OK]

Common Mistakes:

• Assuming text type improves date calculations
• Believing Power BI ignores data types in visuals
• Thinking refresh fixes data type issues

5. You have a column 'Price' imported as Text with values like '12.50', '15.00', and '9.99'. You want to calculate the total price in a measure. Which steps correctly fix the data type and calculate the total?

hard

A. Change 'Price' to Decimal Number in Power Query, then use Total Price = SUM('Table'[Price])

B. Keep 'Price' as Text and use Total Price = CONCATENATE('Table'[Price])

C. Change 'Price' to Whole Number and use Total Price = SUM('Table'[Price])

D. Change 'Price' to Date and use Total Price = SUM('Table'[Price])

Solution

1. Step 1: Identify correct data type for decimal prices

   Prices with decimals require Decimal Number type, not Whole Number or Text.

2. Step 2: Use SUM on Decimal Number column

   SUM works on numeric types, so after changing type, Total Price = SUM('Table'[Price]) calculates total correctly.

3. Final Answer:

   Change 'Price' to Decimal Number in Power Query, then use Total Price = SUM('Table'[Price]) -> Option A

4. Quick Check:

   Decimal type + SUM = correct total [OK]

Hint: Use Decimal Number for prices with decimals [OK]

Common Mistakes:

• Using Whole Number loses decimals
• Concatenating text instead of summing
• Changing price to Date type causes errors