SELECTEDVALUE and HASONEVALUE in Power BI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the DAX function SELECTEDVALUE do?

SELECTEDVALUE returns the single value when there is exactly one value selected in a column. If there are multiple or no values, it returns a default value you specify or blank.

beginner

How does HASONEVALUE differ from SELECTEDVALUE?

HASONEVALUE returns TRUE if exactly one distinct value is selected in a column, otherwise FALSE. It is a logical check, while SELECTEDVALUE returns the actual value or default.

beginner

Write a simple DAX expression using SELECTEDVALUE to get the selected product name or "No Product" if none or multiple are selected.

SelectedProduct = SELECTEDVALUE(Products[ProductName], "No Product")

intermediate

Why would you use HASONEVALUE in a measure?

Use HASONEVALUE to check if a filter or slicer has exactly one value selected. This helps to write conditional logic, like showing detailed info only when one item is selected.

beginner

What will SELECTEDVALUE(Column) return if multiple values are selected?

It returns blank (empty) unless you provide a default value as the second argument.

What does SELECTEDVALUE(Column, "Default") return if no value is selected?

A "Default"

B Blank

C Error

D First value in column

If no value or multiple values are selected, SELECTEDVALUE returns the default value you provide, here "Default".

Which function returns TRUE or FALSE based on whether exactly one value is selected?

A SELECTEDVALUE

B HASONEVALUE

C VALUES

D FILTER

HASONEVALUE returns TRUE if exactly one distinct value is selected, otherwise FALSE.

If you want to show a message when multiple products are selected, which function helps detect this?

A CALCULATE

B SELECTEDVALUE

C SUM

D HASONEVALUE

HASONEVALUE helps detect if exactly one product is selected. If FALSE, multiple or no products are selected.

What will SELECTEDVALUE(Product[Name]) return if exactly one product is selected?

A The selected product name

B Blank

C Error

D All product names

When exactly one value is selected, SELECTEDVALUE returns that value.

Which of these is a correct use of HASONEVALUE in a measure?

A SUM(Category[Sales])

B SELECTEDVALUE(Category[Name])

C IF(HASONEVALUE(Category[Name]), "One", "Many")

D FILTER(Category, HASONEVALUE(Category[Name]))

This expression checks if exactly one category is selected and returns "One" or "Many" accordingly.

Explain in your own words how SELECTEDVALUE and HASONEVALUE work and when you would use each.

Think about selecting one item vs checking if only one item is selected.

Describe a simple scenario in a report where using HASONEVALUE improves user experience.

Imagine a product detail page that only shows details if one product is chosen.

Practice

1. What does the SELECTEDVALUE function do in Power BI?

easy

A. Filters the data to only one selected value

B. Checks if exactly one value is selected

C. Returns all selected values as a list

D. Returns the single selected value or a default if multiple values are selected

Solution

1. Step 1: Understand the purpose of SELECTEDVALUE

   SELECTEDVALUE returns a single value if only one is selected; otherwise, it returns a default or blank.

2. Step 2: Compare with other options

   HASONEVALUE checks selection count, not returning the value itself; other options describe different behaviors.

3. Final Answer:

   Returns the single selected value or a default if multiple values are selected -> Option D

4. Quick Check:

   SELECTEDVALUE = single value or default [OK]

Hint: SELECTEDVALUE gives one value or default if many selected [OK]

Common Mistakes:

• Confusing SELECTEDVALUE with HASONEVALUE
• Thinking SELECTEDVALUE returns all selected values
• Assuming SELECTEDVALUE filters data

2. Which of the following is the correct syntax for using HASONEVALUE in a DAX measure?

easy

A. HASONEVALUE = ColumnName

B. HASONEVALUE[ColumnName]

C. HASONEVALUE(ColumnName)

D. HASONEVALUE(ColumnName, DefaultValue)

Solution

1. Step 1: Recall HASONEVALUE syntax

   HASONEVALUE takes a single column as argument to check if exactly one value is selected.

2. Step 2: Eliminate incorrect syntax

   Options A, C, and D do not follow correct function call syntax or add invalid parameters.

3. Final Answer:

   HASONEVALUE(ColumnName) -> Option C

4. Quick Check:

   HASONEVALUE(Column) syntax correct [OK]

Hint: HASONEVALUE takes one column as argument in parentheses [OK]

Common Mistakes:

• Using equal sign instead of parentheses
• Adding extra parameters to HASONEVALUE
• Using square brackets incorrectly

3. Given the following DAX measure:

Selected Product = SELECTEDVALUE('Products'[ProductName], "Multiple")

If the user selects exactly one product named "Chair", what will the measure return?

medium

A. "Chair"

B. "Multiple"

C. Blank

D. Error

Solution

1. Step 1: Understand SELECTEDVALUE behavior with one selection

   When exactly one value is selected, SELECTEDVALUE returns that value, here "Chair".

2. Step 2: Consider the default value

   The default "Multiple" is returned only if multiple or no values are selected, which is not the case here.

3. Final Answer:

   "Chair" -> Option A

4. Quick Check:

   One value selected = returns that value [OK]

Hint: One selected value returns it, else default [OK]

Common Mistakes:

• Assuming default value returns even with one selection
• Confusing blank with default
• Expecting error on multiple selections

4. You wrote this DAX measure:

IsSingleCategory = IF(HASONEVALUE('Sales'[Category]), SELECTEDVALUE('Sales'[Category]), "Multiple")

But it always returns "Multiple" even when one category is selected. What is the likely problem?

medium

A. The HASONEVALUE function is used incorrectly without a filter context

B. SELECTEDVALUE cannot be used inside IF statements

C. The column name 'Category' is misspelled

D. The measure lacks a default value in SELECTEDVALUE

Solution

1. Step 1: Analyze HASONEVALUE usage

   HASONEVALUE depends on filter context; if no filter is applied, it returns FALSE even if one value exists.

2. Step 2: Understand why measure returns "Multiple"

   Without proper filter context, HASONEVALUE returns FALSE, so IF returns "Multiple" always.

3. Final Answer:

   The HASONEVALUE function is used incorrectly without a filter context -> Option A

4. Quick Check:

   HASONEVALUE needs filter context to work [OK]

Hint: HASONEVALUE needs filter context to return TRUE [OK]

Common Mistakes:

• Assuming SELECTEDVALUE can't be inside IF
• Ignoring filter context importance
• Not checking column spelling

5. You want to create a measure that shows the selected product name if exactly one product is selected, otherwise shows "Multiple Products". Which DAX expression correctly achieves this?

hard

A. Product Selected = IF(SELECTEDVALUE('Products'[ProductName]), HASONEVALUE('Products'[ProductName]), "Multiple Products")

B. Product Selected = IF(HASONEVALUE('Products'[ProductName]), SELECTEDVALUE('Products'[ProductName]), "Multiple Products")

C. Product Selected = SELECTEDVALUE('Products'[ProductName], HASONEVALUE('Products'[ProductName]))

D. Product Selected = HASONEVALUE('Products'[ProductName]) & SELECTEDVALUE('Products'[ProductName])

Solution

1. Step 1: Understand the requirement

   Show product name if exactly one selected; else show "Multiple Products".

2. Step 2: Evaluate each option

   Product Selected = IF(HASONEVALUE('Products'[ProductName]), SELECTEDVALUE('Products'[ProductName]), "Multiple Products") uses HASONEVALUE to check selection count and SELECTEDVALUE to get the name, with fallback text. Others misuse functions or syntax.

3. Final Answer:

   Product Selected = IF(HASONEVALUE('Products'[ProductName]), SELECTEDVALUE('Products'[ProductName]), "Multiple Products") -> Option B

4. Quick Check:

   HASONEVALUE + SELECTEDVALUE with IF = correct pattern [OK]

Hint: Use IF with HASONEVALUE and SELECTEDVALUE for conditional display [OK]

Common Mistakes:

• Passing HASONEVALUE as default to SELECTEDVALUE
• Using SELECTEDVALUE as condition in IF
• Concatenating HASONEVALUE and SELECTEDVALUE incorrectly