Michael Kellett – Mym111

Data Analysis Expressions (DAX) is a powerful formula language used in Microsoft Power BI, Excel Power Pivot, and SQL Server Analysis Services (SSAS). It allows users to create calculated columns, measures, and custom tables to derive insights from their data. While there are many DAX functions, some are far more essential than others. This article will focus on the top 10 most frequently used and essential DAX formulas that every analyst should know, along with their common combinations.

1. CALCULATE() with FILTER()

Why It’s Essential

CALCULATE() is arguably the most powerful DAX function because it allows users to modify the filter context in which an expression is evaluated. It is often combined with FILTER() to apply complex conditions.

Example:

CALCULATE(SUM(Sales[Revenue]), FILTER(Sales, Sales[Region] = "North America"))

If the Sales table contains revenue values such as $10,000 from North America and $5,000 from Europe, this formula returns $10,000 by summing only the North American sales.

2. SUMX() with RELATED()

Why It’s Essential

SUMX() performs row-by-row calculations, making it flexible when working with related tables. RELATED() is used to fetch values from another table based on relationships.

Example:

SUMX(Sales, Sales[Quantity] * RELATED(Products[Price]))

If a Sales table has 5 units of Product A (priced at $20) and 3 units of Product B (priced at $15), this formula returns a total revenue of $145 (5×$20 + 3×$15).

3. RANKX() with ALL()

Why It’s Essential

RANKX() is essential for ranking items in a dataset. Using ALL() ensures that ranking is done across the entire dataset, ignoring filters.

Example:

RANKX(ALL(Sales), SUM(Sales[Revenue]), , DESC, DENSE)

If three salespeople have total revenues of $50,000, $75,000, and $60,000, this formula assigns them ranks 2, 1, and 3, respectively, ensuring ranking is based on total revenue.

4. DISTINCTCOUNT() with CALCULATE()

Why It’s Essential

DISTINCTCOUNT() is commonly used in KPIs, and using CALCULATE() allows conditional unique counts.

Example:

CALCULATE(DISTINCTCOUNT(Sales[CustomerID]), Sales[Region] = "West")

If the West region has 10 customer transactions but only 7 unique customers, this formula returns 7, reflecting distinct customer engagement.

5. SELECTEDVALUE() for Dynamic Measures

Why It’s Essential

SELECTEDVALUE() helps return the currently selected value in a filter context, commonly used in dynamic reports.

Example:

SELECTEDVALUE(Sales[Product], "Multiple")

If a user selects “Laptop,” the function returns “Laptop”; if multiple products are selected, it returns “Multiple.”

6. VAR and RETURN for Readability

Why It’s Essential

VAR allows defining variables within a formula, making calculations easier to read and optimize.

Example:

VAR Discount = 0.1 * SUM(Sales[Revenue])
RETURN SUM(Sales[Revenue]) - Discount

If total revenue is $50,000, this formula calculates a 10% discount ($5,000) and returns $45,000.

7. DATEADD() with TOTALYTD()

Why It’s Essential

Used extensively in time intelligence calculations, DATEADD() shifts dates, while TOTALYTD() calculates Year-To-Date values.

Example:

TOTALYTD(SUM(Sales[Revenue]), Sales[OrderDate])

If a company generated $30,000 in January, $40,000 in February, and $35,000 in March, this formula returns $105,000 when used at the end of March.

8. LOOKUPVALUE() for Data Retrieval

Why It’s Essential

Fetches a value from another column in a related or unrelated table, replacing traditional VLOOKUP-like functionality.

Example:

LOOKUPVALUE(Products[Category], Products[ProductID], Sales[ProductID])

If ProductID 101 corresponds to “Electronics,” this formula returns “Electronics” for all sales transactions involving ProductID 101.

9. COUNTROWS() with FILTER()

Why It’s Essential

Counts the number of rows in a table, commonly used in summary calculations and combined with FILTER() for conditional counting.

Example:

COUNTROWS(FILTER(Sales, Sales[Revenue] > 1000))

If there are 50 total transactions but only 20 exceed $1,000, this formula returns 20, providing insights into high-value sales.

10. HASONEVALUE() for Dynamic Titles and Calculations

Why It’s Essential

Checks whether there is a single value in the filter context, useful for dynamic formatting in reports.

Example:

IF(HASONEVALUE(Sales[Product]), SELECTEDVALUE(Sales[Product]), "Multiple Products Selected")

If a report is filtered to “Headphones,” this formula displays “Headphones”; if multiple products are selected, it displays “Multiple Products Selected.”

Final Thoughts

These 10 DAX functions cover a broad range of analysis needs, from filtering and ranking to time intelligence and relationship functions. More importantly, they are often used together to create complex yet efficient calculations.

If you’re just starting, focus on understanding CALCULATE(), SUMX(), and FILTER() as they form the backbone of advanced DAX calculations. From there, explore ranking, time intelligence, and lookup functions to further enhance your analytical capabilities.