SAMEPERIODLASTYEAR in Power BI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to calculate sales for the same period last year.

Power BI

Sales LY = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR([1]))

Drag options to blanks, or click blank then click option'

ASales[Amount]

BCalendar[Date]

CSales[Date]

DCalendar[Year]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-date column inside SAMEPERIODLASTYEAR.

Using the sales amount column instead of a date column.

The SAMEPERIODLASTYEAR function requires a date column from a calendar or date table. Here, Calendar[Date] is the correct date column.

2fill in blank

medium

Complete the code to calculate last year's sales filtered by product category.

Power BI

Sales LY Category = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR([1]), FILTER(Products, Products[Category] = "Bikes"))

Drag options to blanks, or click blank then click option'

ASales[Date]

BProducts[Category]

CCalendar[Date]

DSales[Category]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a category column inside SAMEPERIODLASTYEAR.

Confusing the filter context with the date argument.

The SAMEPERIODLASTYEAR function needs a date column, so Calendar[Date] is correct. The filter on product category is separate.

3fill in blank

hard

Fix the error in the code to correctly calculate sales for the same period last year.

Power BI

Sales LY = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR([1]))

Drag options to blanks, or click blank then click option'

ACalendar[Date]

BProducts[Date]

CSales[Date]

DSales[Amount]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a measure or amount column instead of a date column.

Using a date column from a fact table instead of a calendar table.

The error is using a non-calendar date column. Calendar[Date] is the correct date column for SAMEPERIODLASTYEAR.

4fill in blank

hard

Fill both blanks to calculate last year's sales for a selected month and year.

Power BI

Sales LY Selected = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR([1]), FILTER(ALL(Calendar), Calendar[Month] = [2]))

Drag options to blanks, or click blank then click option'

ACalendar[Date]

BCalendar[Month]

C"January"

DSales[Month]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-date column in SAMEPERIODLASTYEAR.

Using a column name instead of a string for the month filter.

The first blank needs the date column for SAMEPERIODLASTYEAR, which is Calendar[Date]. The second blank is the month filter value, here the string "January".

5fill in blank

hard

Fill all three blanks to calculate last year's sales filtered by year and product color.

Power BI

Sales LY Filtered = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR([1]), FILTER(ALL(Calendar), Calendar[Year] = [2]), FILTER(Products, Products[Color] = [3]))

Drag options to blanks, or click blank then click option'

ACalendar[Date]

B2022

C"Red"

DSales[Year]

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fact table column instead of calendar date.

Using strings instead of numbers for year filter or vice versa.

Not quoting the color string.

The date column for SAMEPERIODLASTYEAR is Calendar[Date]. The year filter uses the number 2022. The product color filter uses the string "Red".

Practice

1. What is the main purpose of the SAMEPERIODLASTYEAR function in Power BI?

easy

A. To calculate the total sales for the current year

B. To compare data from the same period in the previous year

C. To filter data for the current month only

D. To create a new date column with next year's dates

Solution

1. Step 1: Understand the function's purpose

   SAMEPERIODLASTYEAR shifts the date context back exactly one year to compare the same time periods.

2. Step 2: Identify the correct use case

   It is used to compare measures like sales or revenue from this year to the same period last year.

3. Final Answer:

   To compare data from the same period in the previous year -> Option B

4. Quick Check:

   SAMEPERIODLASTYEAR compares last year's period [OK]

Hint: Think "same time last year" for comparison [OK]

Common Mistakes:

• Confusing it with total aggregation functions
• Using it to filter current year data
• Assuming it creates future dates

2. Which of the following is the correct syntax to use SAMEPERIODLASTYEAR with a date column named Sales[Date]?

easy

A. SAMEPERIODLASTYEAR('Sales'[Date])

B. SAMEPERIODLASTYEAR(Sales[Date])

C. SAMEPERIODLASTYEAR(Sales.Date)

D. SAMEPERIODLASTYEAR([SalesDate])

Solution

1. Step 1: Recognize correct table and column reference

   In DAX, table and column names are referenced as 'TableName'[ColumnName], so 'Sales'[Date] is correct.

2. Step 2: Check syntax correctness

   SAMEPERIODLASTYEAR(Sales[Date]) omits single quotes around the table name. SAMEPERIODLASTYEAR(Sales.Date) uses invalid dot notation. SAMEPERIODLASTYEAR([SalesDate]) uses an incorrect column name format.

3. Final Answer:

   SAMEPERIODLASTYEAR('Sales'[Date]) -> Option A

4. Quick Check:

   Correct DAX column reference uses quotes and brackets [OK]

Hint: Use single quotes for table, brackets for column [OK]

Common Mistakes:

• Omitting single quotes around table name
• Using dot notation instead of brackets
• Referencing columns without table name

3. Given the measure:

Sales LY = CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date]))

If total sales for March 2023 are 1000, and for March 2022 are 800, what will Sales LY show when filtered on March 2023?

medium

A. 800

B. 1800

C. 1000

D. 0

Solution

1. Step 1: Understand the measure calculation

   The measure sums sales amounts but shifts the date filter to the same period last year using SAMEPERIODLASTYEAR.

2. Step 2: Apply the filter context for March 2023

   When filtered on March 2023, the measure returns sales from March 2022, which is 800.

3. Final Answer:

   800 -> Option A

4. Quick Check:

   Sales LY shows last year's same period sales [OK]

Hint: SAMEPERIODLASTYEAR shifts filter to last year [OK]

Common Mistakes:

• Assuming it sums current year sales
• Adding current and last year sales
• Returning zero if no explicit filter

4. You wrote this measure:

Sales LY = CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR(Sales[Date]))

But it returns an error. What is the likely cause?

medium

A. Measure name cannot contain spaces

B. SUM function cannot be used inside CALCULATE

C. SAMEPERIODLASTYEAR requires a numeric column

D. Missing single quotes around the table name 'Sales'

Solution

1. Step 1: Check table and column references

   The table name 'Sales' must be enclosed in single quotes when referenced in DAX, so Sales[Date] is invalid.

2. Step 2: Understand function requirements

   SUM inside CALCULATE is valid, SAMEPERIODLASTYEAR requires a date column, and measure names can have spaces.

3. Final Answer:

   Missing single quotes around the table name 'Sales' -> Option D

4. Quick Check:

   Table names need single quotes in DAX [OK]

Hint: Always quote table names in DAX formulas [OK]

Common Mistakes:

• Forgetting single quotes around table names
• Thinking SUM can't be inside CALCULATE
• Assuming SAMEPERIODLASTYEAR needs numeric columns

5. You want to create a measure that shows the percentage change in sales compared to the same period last year. Which DAX formula correctly uses SAMEPERIODLASTYEAR to calculate this?

hard

A. Sales YoY % = CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])) - SUM('Sales'[Amount])

B. Sales YoY % = SUM('Sales'[Amount]) / SAMEPERIODLASTYEAR('Sales'[Date])

C. Sales YoY % = DIVIDE(SUM('Sales'[Amount]) - CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])), CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])))

D. Sales YoY % = SUM('Sales'[Amount]) - CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date]))

Solution

1. Step 1: Understand the percentage change formula

   Percentage change = (Current - Previous) / Previous, so we need current sales minus last year's sales divided by last year's sales.

2. Step 2: Analyze each option

   Sales YoY % = DIVIDE(SUM('Sales'[Amount]) - CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])), CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date]))) correctly uses DIVIDE to avoid errors and calculates the difference over last year's sales. Sales YoY % = SUM('Sales'[Amount]) / SAMEPERIODLASTYEAR('Sales'[Date]) divides sales by a date column, which is invalid. Sales YoY % = CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])) - SUM('Sales'[Amount]) subtracts current from last year without division. Sales YoY % = SUM('Sales'[Amount]) - CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])) calculates difference but not percentage.

3. Final Answer:

   Sales YoY % = DIVIDE(SUM('Sales'[Amount]) - CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date])), CALCULATE(SUM('Sales'[Amount]), SAMEPERIODLASTYEAR('Sales'[Date]))) -> Option C

4. Quick Check:

   Percentage change = (Current - LastYear) / LastYear [OK]

Hint: Use DIVIDE for safe percentage calculations [OK]

Common Mistakes:

• Dividing by a date column instead of sales
• Forgetting to divide difference by last year's sales
• Subtracting without calculating percentage