Parameters in DAX – Introduction into DAX Expressions

DAX language haves its standards as does any other language. This article sums up and describes how look the parameters of formulas. In other words, this article is about function arguments overview.  It is good to know parameter categories appearing in this language to effectively use parameters in DAX.

What is Function Parameter in DAX?

Demonstration – in the screenshot is function LOOKUPVALUE. It is equivalent of Excel function VLOOKUP. The function works similarly. It returns column value in table A based on match of other column in table A with value in table B.

Parameters in this case are:

  • Result_ColumnName – name of the column containing the value wanted to be returned using function
  • Search_ColumnName – name of the column in which the value is located and based on which we search for match in column Result_ColumnName
  • Search_Value – value based on which we search for match

Parameters in DAX – Names and Descriptions

1) Expression – call sign for an expression returning scalar value. Each expression is evaluated for each row of the table. Lower is the example of sum function. It calculates total sum of all sales amounts in a table.

[Total Sales] =SUM ([Sales_Amount])

But the expression can be only:

dax parameters - expressions vs functions

[Total Sales] =[Sales_Amount]*2

2) Table – expression returning other table as a result. In the example, it can be seen how to generate list of dates between 2 two bordering dates. All done using function CALENDAR.

[Calendar] := CALENDAR(DateStart; DateEnd)

3) TableName – name of an existing table. In this case is the name of the table argument of function SUMX. We perform sum in table “Table_With_Sales” of expression Amount after discount.

[Amount after discount] :=SUMX ([Table_With_Sales];[Sales_Amount]* ( 1 - [Discount %] ))

4) Column name – similar to 3) TableName – it is a name of column in existing table. It is being used as function argument – for example already mentioned LOOKUP

5) Name – Text constant expressing name of new object (column in a table)

Dax parameters and expressions - name of a new column

6) Order – In functions, it is possible to use parameter which for any reason organizes our data in descending (DESC) or ascending (ASC) order. Example of this can be function TOPN. It returns TOP X values from any table organized by some value. We need to tell it by what it should guide itself (ASC/DESC) so it will be possible for it to return result of TOP X values.

= TOPN (15,Employees,Employee[LastName],ASC)

7) Ties – Parameters characteristic for many advanced functions. According Excel equivalent might be last logical function parameter VLOOKUP (approximate/exact value)

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About Ing. Jan Zedníček - BI Developer, Finance controller

My name is Jan Zedníček and I work as a BI Developer at Kentico Software in Brno. Mostly you can see me there working in the office, but I also work partly as a freelancer. I have been working as a freelancer for many companies for more than 5 years, but Kentico is the matter of my heart. I used to work as a financial controller at companies like Aero Vodochody, banking and I also used to be a bond program manager in Unicapital Investment group. When I am not at work, I like playing volleyball, chess, doing a workout in the gym and I enjoy tasting of best quality rums. I am trying to summarize all my knowledge on this website not to forget them (because of the rum effect, you know =) and to put them forward to anyone. Don´t worry about asking for help or writing some comments.

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