Tuesday 26 December 2023

What is Dax Function that is used in Power BI ? Power BI interview questions and answers 125

Power BI  interview questions and answers

DAX (Data Analysis Expressions) is a formula language specifically designed for data analysis and manipulation in Power BI and other Microsoft data tools. It offers a rich set of functions to perform various calculations, create measures, and transform data. Here are key categories of DAX functions:

1. Aggregation Functions:

  • Calculate summary values over a group of rows, such as:

  • SUM: Calculates the sum of values.

  • AVERAGE: Calculates the average value.

  • MIN: Returns the minimum value.

  • MAX: Returns the maximum value.

  • COUNT: Counts the number of non-empty values.

  • DISTINCTCOUNT: Counts the number of unique values.

2. Date and Time Functions:

  • Work with date and time data, such as:

  • YEAR: Extracts the year from a date.

  • MONTH: Extracts the month from a date.

  • DAY: Extracts the day from a date.

  • DATEADD: Adds or subtracts a specified number of days, months, or years to a date.

  • DATEDIFF: Calculates the difference between two dates in terms of days, months, or years.

3. Logical Functions:

  • Perform logical operations and comparisons, such as:

  • IF: Returns one value if a condition is true and another value if false.

  • AND: Returns TRUE if all conditions are true.

  • OR: Returns TRUE if at least one condition is true.

  • NOT: Reverses the logical value of its argument.

4. Information Functions:

  • Get information about data or calculations, such as:

  • HASONEVALUE: Checks if a column has only one distinct value.

  • ISBLANK: Checks if a value is blank.

  • ERROR: Returns an error value.

  • SELECTEDVALUE: Returns the selected value from a filter context.

5. Mathematical Functions:

  • Perform mathematical operations, such as:

  • ABS: Returns the absolute value of a number.

  • ROUND: Rounds a number to a specified number of decimal places.

  • SQRT: Calculates the square root of a number.

6. Text Functions:

  • Manipulate text values, such as:

  • CONCATENATE: Combines multiple text strings into a single string.

  • LEN: Returns the length of a text string.

  • UPPER: Converts text to uppercase.

  • LOWER: Converts text to lowercase.

7. Time Intelligence Functions:

  • Perform calculations over time periods, such as:

  • TOTALYTD: Calculates the year-to-date total for a measure.

  • SAMEPERIODLASTYEAR: Calculates the value for the same period in the previous year.

  • DATESYTD: Returns a set of dates from the beginning of the year to the specified date.

8. Filter Functions:

  • Manipulate filter context, such as:

  • FILTER: Returns a table filtered based on specified conditions.

  • ALL: Removes all filters from a table.

  • ALLSELECTED: Returns all rows in the current filter context, including those with blank values.

9. Other Useful Functions:

  • RANKX: Assigns a rank to values within a group.

  • LOOKUPVALUE: Returns a value from another table based on a matching condition.

  • RELATED: Retrieves values from a related table.

  • CALCULATE: Modifies filter context within a calculation.

Remember: DAX functions are always used within a formula context, such as creating measures or calculated columns. They cannot be used directly on a visual or table.

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